I'd try to see if there are used record/CD stores. Maybe you could even dicker on price. I'd try areas near colleges and universities. We have a very large university near me and used music is easy to come by. There are used book stores that also have CDs. At least you'd get to look at their condition which is something you'd not get with Amazon. Another source you can look into is libraries. I don't mean you should borrow and rip music but libraries take donations and sell stuff off.
I've seen the stuff on Amazon and I do wonder about shipping costs. Amazon does offer free shipping for $25 and over but I believe that's only for what they stock or "fulfill". Amazon fulfillment means they have space in their warehouses for vendors and store merchandise on those sites so they also handle the shipping. A two buck CD will be several dollars to ship.
Good luck in your treasure hunt.
I was divorced in 1999 and my ex-wife and I split the music collection. Well I've been building that collection back up over the last few years. In the wee hours og the morning I discovered that Amazon sold used CD's but they're coming from vendors from all points on the compass . Some of these are like .99 cents or $2.00. It varies. Has anyone used this venue in this fashion ? Is it safe because i'm racking up quite the list of used music. Thanks for your time...Digger