Buying Trained Animals

[AuraSeer]

Has anyone published a price list for trained animals, other than the standard horses and dogs from the PHB? If not, what do you do if a PC wants to ride a camel or a dire boar, or keep a guard tyrannosaur in his backyard?

(Availability is hardly an issue. I'm assuming that with teleportation and planar travel, the party can find a salesperson for just about anything, if they look hard enough.)

 

[Winternight]

Stronghold builders guide and arms and equipmentguide also in the monster manual (at least 3.0, dunno about 3.5)