I can get these wheels made up.
they have an outer diameter of 50mm and inner diameter 10mm.

They are made from FR4, the same stuff good PCBs are made from.
They will be very strong, balanced and run true.
The cost will be $4 each for orders of 30 and over.

I can also make them with custom logo's and cutouts.

Click on image for a larger view.

Interesting man, nice way to get a bit of extra advertising. By the way, at four bux each it's a low cost alternative for an excellent quality product.

What would the weight of them be like compared to the aluminum or nylon wheels?

They will weigh just as much as a carbon fiber wheel will the same size.
Strength wise, allot stronger than nylon, and more rigid than aluminum.

They will be machined perfectly to the micron, so you wont have problems
with them not running true.

They can be blank, i don't have to have the logo there.
They can be made in various sizes as well.