Do Not Buy a Used Acceledent on eBay! Here's Why....
First there is the hygiene factor. Do you really want to use a mouthpiece that has been in someone else's mouth? Yuck!
Secondly, the Acceledent appliance is programmed to stop working after a certain period of time (usually around 10,000 minutes -- about 18 months of daily use). This means that you could buy a used Acceledent, and it might stop working after a month or two. Most people don't know how many minutes they have used the device, or how many minutes are left on it. It can't be reprogrammed, so you've essentially spent a lot of money for a paperweight after it dies.
Thirdly, it's ILLEGAL to sell a used Acceledent! The FDA has classified this appliance in such a way that only dental offices can sell it to patients. It's against FDA regulations for the Acceledent to be sold in any retail setting! So, those eBay sellers are breaking the law, and you are abetting them by buying an illegally sold dental appliance!
If you're looking for a less expensive alternative to Acceledent for braces pain, check out Viber. It does essentially the same thing as Acceledent, but it costs less than $200. Viber doesn't stop working after a period of time -- you can use it as long as you need, and even pass it on to your kids (or sell/give it to someone else along with a new clean mouthpiece) and it will work just as well. It's rechargeable and you can readily buy new mouthpieces for it. (FYI, Viber is the new version of BitePod20 -- it now plugs into the wall with a USB cord, so it doesn't need disposable batteries anymore).
You can find Viber on DentaKit.com at: https://www.dentakit.com/bitepod20.html Use the coupon code FreeShip69 to get free shipping on Viber, or any order with a subtotal of $69 or more.