Yeah, I love my Warbeasts. They have a set cost in the template (in MMII) for those who don't know... my traditional mount for any stealther type is a Magebreed Warbeast Desmoderu Hunting Bat. Cheap, stealthy, and decent in combat for its price, plus it can go anywhere and can detect invisible enemies (note the errata though, it has Blindsense not Blindsight). Up it by one HD if you're a medium sized character.
Plus, I don't think I've ever made a starting level 1 character without a Magebreed Donkey or Mule. At 16gp they're too cheap to worry about, and they can carry PLENTY of stuff, plus they can fight decently (ish)!
JaronK