And AFAIC, I don't know why anyone would buy used kegs any more. You can get new ones on sale for within 5 bucks of what you'd pay for used ones. Seems like a no-brainer to me.
The last time I bought used kegs (maybe 12 months ago) I got them for $40 each and I think it was free shipping. AiH has some nice sales on a regular basis. That's a lot more than $5 less and when I finally got around to cleaning them up they were in great condition. I love the smaller kegs, but I just can't justify spending more money on them. Plus I don't need any kegs. I have way too many.
For small kegs, I've also bought used pin-locks from AiH. Again I want to say it was something like $40 per keg, delivered. I thought about changing out the posts to ball lock, but it was cheaper just to buy some pin-lock fittings. All my lines have flare fittings, so changing them is simple.