Quote Originally Posted by qwertyu63 View Post

Are there listed prices for buying animals anywhere?
A16 (Partial) Yes.

The SRD has a link under Goods and Services, Mounts and Related Gear.

Other animals may have listed prices in their entry in the various monster manuals or books where they were introduced. For example the Battletitan Dinosaur (MM3, p38) has a cost of "often more than 100,000 gp." Eberron Campaign Setting has prices for various animals on page 121. If no price is listed, it is up to the individual DM to set a price, and even if the creature is available for purchase at all.