Gently used solo dresses - How To!

Buying a solo dress for the first time - or the fifth time - is scary. It's a hefty purchase to make, and pictures just can't convey everything about a dress. So how do you try to minimize your risk when purchasing a dress online?
We've bought three solo dresses so far. The first two we found on Dance-Again, a wonderful site run by Lisa in Australia that lists thousands of dresses. The third dress was a brand-new, off-the-rack we found on eBay (see my post about my dancer's newest dress below). We've had amazing luck both buying and selling - and we've learned a lot about the process.
The first step is to graze around all the sites that list dresses. Here are some:

Dance Again

Antonio Pacelli Dress Exchange

Irish Dancing Exchange

Dance Spirit

McGahan Lees Dress Exchange

Make sure you look at all possible age and size categories on these sites, because often a dress the seller owned for their small 12 year old, would actually fit your tall 10 year old. As for measurements, most often those listed are the dress measurements, not of the dancer who would fit the dress (make sure to ask the seller which is the case).
Here are the measurements you need (your teacher may be able to help, or find a seamstress if you're unsure of how to measure): bust, waist, nape of neck to waist, waist to hem, inner and outer sleeve. Some dresses now have a dropped waist, and you'll also want to have an idea of a total dress length so you can judge the nape to waist and waist to hem according to overall length. If you have a well-fitting school dress, you can measure it to get an idea of what size you need. But remember, those usually have a much longer skirt than a solo dress would. Also, if anyone in your school is the same size as your dancer, you could ask to try on their dress and measure it as another way to be more certain of the measurements.
After you've found dresses online that you and your dancer both like - and that are within your price range - you need to contact the sellers and gather more information. Often times, you'll find that the dresses are no longer available, but the listing just hasn't been deleted. That's why you need to have several dresses in mind. If you get captivated by one and then it's not for sale, you may be so disappointed that nothing else compares.
Here are things you need to know (some of these may be answered in the listing, if not, be sure to inquire):
Does the seller know who made the dress?
Do they have any photos of the dress on a dancer? What about pictures of the underskirt, cuffs or lining?
What specific wear and tear does the dress have?
Does the dress have any odors (b.o. from the dancer, or smoke from a house with smokers) or stains (particularly fake tan)?
What is the history of the dress? How much did they pay for it? How long have they owned it?
How does the seller want payment? How much for shipping and insurance?
Will they take a return on it if it doesn't fit (you'll need to expect to pay the return shipping)?
Once you have the answers, you can narrow your choices. You'll also want to consider ...
The dress fabric: main fabrics for these dresses have peaked and waned in popularity in recent years.
Gabardine was one of the first post-velvet fabrics, and usually means a dress is at least four or five years old. It's pretty durable and cleanable (with handiwipes), so if your budget is fairly limited and you like the design, this can be a fine choice for a first dress. It's probably suitable only for Novice competition, but ask your teacher's opinion.
Glitter square rose to popularity a few years ago when the glitz in Irish Dancing really took hold. It sparkles like crazy, but it's VERY heavy and hot, so your poor dancer is essentially armored in plastic. And the wear and tear on these is brutal - those squares peel away rampantly. Glitter square is used mostly now for applique only.
Glitter dot can be better. Depending on the dress construction, it's a good choice for a Novice or Prizewinner dancer. Make sure the bodice is lined though, as the fabric needs extra support in order to hang well. Also, those little dots disappear like mad from wear and tear - especially anywhere there's friction, such as the inside of the sleeve, which rubs against the bodice.
Silk is classic and always in style. It's a beautiful, sophisticated choice, and highly recommended for any level dancer. One thing to watch for on a used dress, though, is wear and tear on the hemmed edges. Silk tends to fray, and you may see some of that on the bottom hems or on the corners of the skirt panels. Be sure to ask the seller about this as it is not repairable.
The newest dresses are using lots of organza and lace overlays, brocades, silks, lycras, and just about any embellished fabric you can dream up. If your budget allows, there are some amazing, nearly haute couture creations out there.
You'll also want to look at the dress' features: Does it have modern elements, such as shaped pleats and hem? Is the cape a small, bum-style? If it's older, does the cape attach with velcro near the shoulders (this does a number on wigs, so it's something to consider)?
The dressmaker also may impact your decision. The top large dressmakers are Siopa Rince (classic, elegant and very detailed) and Gavin Doherty (innovative and experimental). Smaller companies with good reputations are Aine Designs, Celtic Originals, Dancing in Celtic (Ann Ash) and Shamrock Stitchery. There are lots of individual dressmakers with great names, too, such as Paddy Kelleher, Andrea Yates, Veronica Carroll, Eileen Plater, Sheila Hayes, Jess Knight, Dorothy Ryan, Michelle Lewis and many more. And I know there are many other talented dressmakers!
When you think you've found the dress, you've verified that it's available and you've run it past your dancer teacher for approval (this is a must!), then it's time to make an offer. You can usually offer less than what the seller is asking - it's like buying a house. You make one offer, sometimes they accept, and sometimes they counter and you meet in the middle.
However if a dress is priced right, it will sell in no time, so you need to be ready to make a decision quickly once you feel sure you've found the right seller and the right dress. After you both agree to a price, be sure to request tracked shipping through UPS, FedEx, etc. as well as insurance.
We have always used PayPal to conduct transactions. It has some level of fraud protection and the payment is immediate. There is a small fee, but we've always felt it was worth that. Depending on your location and that of your seller, there may be customs issues. We have bought dresses from both Scotland and England for shipment to the U.S. Both times the items were marked as Clothing/Costume, and we've had no problems. Some countries require additional customs fees for the recipient, so you may need to explore that further.
Once you've paid, the waiting game begins. It's very exciting and frightening to open that box for the first time, but when you've asked all the right questions and feel comfortable with the seller, then you know you've done everything you can to make it a positive experience. Good luck and happy shopping!