Gear types

I have been working on some interesting designs involving worm gears and differentials lately, and one thing I have noticed is a distict lack of worm and differential gears. Metal worm gears tend to cost in the $60-200 range for ones suitable for FRC use, and that’s not including the worm. Plus, I have only been able to find large worm gears with low pitches in metric sizes. Differentials are slightly different. There seems to be a large selection, but most are made for RC vehicles and are not adaptable to FRC at all because of their strange dimensions. I would really like to see metal worm and differential gears in the VEX product line.
I know there is the Advanced Gear Kit, but to me it seems like the gears would be unable to hold up to very heavy loads; plus, they need the smaller shafts.