[asid61]

I vote QTC. Rush Gears has a minimum order on the level of $1500 regardless of number. The gears from QTC are of pretty good quality even at the lowest quality they offer for metal gears, and you can buy ground gears if you need to. They have a very wide selection too.
It's very easy to modify the bevel gears if you sue a machinable collet to hold them; I have been shortening the hubs and widening the bores slightly for a project.