Rabbit Valley's having a nifty 'by the pound' promotion.
Adult is $2/pound, half of it will be Adult-only works.
Mature is $1.50/pound, 2/3rds of it will be Mature-only works.
General is $1/pound, all of which will (obviously) be General-audience works.
If you're patient enough to wait for Media Mail shipping (3-6 weeks in the US) you can get a LOT of furry stuff on the cheap. Only guarantee besides no duplicates in a single order is that it'll all be printed material, but could be anything from comics to fanzines to 'any printed material' to quote their website.