You can get another race's mount within your faction. To do that, however, you must be exalted with that race. For example, I'm human and am currently working on getting myself a Night Elf mount(and the riding skill, which is why I must be exalted). In order to get my reputation up high enough, I'm turning in both Morrowgrain and Runecloth.
This is a slow process or a costly one. For a non-human, it costs 420 stacks of runecloth to go from 0 revered to 0 exalted. For a human, this number is 381.82 stacks(382 since you can't turn in partial stacks)(for all those who would even care .82 stacks is 16.4 individual cloth, not that it matters)
Assuming an average cost of runecloth at 1.5g/stack, that means:
Non-Human 630g
Human 573g
Edit: Forgot to mention, only dwarves and gnomes can ride mechanostriders.
Edited, Sat May 20 01:39:02 2006 by Poldaran