1/4" Carriage bolts can be found at just about any hardware store. Just paint them black or use gun bluing compound on them.
Wade
I considered this. Unfortunately, by the time you buy the screws and the bluing compound and did all the work, you could have just bought a bunch from divemaster for the same price without the work. The bolts he sells are very nice, and for 0.25
I've found that doing things the homebrew way and scrimping and saving usually ends up in an inferior product, and just as much money out of pocket. 
This is true in so many ways, but we are talking about bolts, not a used trackball or 30 year old monitor.

By the posts in this thread, you'd think these things are impossible to find. Every hardware store I've looked in has 1/4 carriage bolts, and Pyle on the West Side near where you work carries 3/16. If you go to the hardware store at least a couple times a week like I do, or are just passing by anyway, why wait a few days by ordering them?
I agree, maybe on a CP or something it is more important, and I order the black ones occasionally too, but I also have bought a LOT of carriage bolts from the local hardware stores (usually, I am using them silver and not black, but I have painted them a few times when needed). A lot of games use the silver ones originally, too.
I'm used to having to paint or blue hardware though because so many of my games have security torx that I HAVE to refurbish (I haven't found found anyone selling them, mail order or not. Anyone here know sources??)
TTYL!
Wade