how about some place that cuts glass for windows and picture frames? Or try a glass cutter, I don't know the price of a glass cutter versus having it cut commercially,but maybe you could invest in one and it would be much cheaper if you're going to have a collection done up:)

How to Cut Glass Disks
By sawing out a round board, laying it flat on a sheet of glass and running your glass cutter around the edge of the pattern you can cut out an approximately round disk of glass. But to cut out a perfectly round disk you must have a circular glass cutter. If you don't want to cut it yourself, try a framing store,craft store or a locally owed hardware store.

Just wondering if maybe clear glass plates would work for your project? Lots easier than cutting glass, and you can find them at Walmart or even TS. Luvs

Michael's Craft stores have framing dept. I think they even sell pic frames that are round so you could just buy 3 of those! Also some cheap metal stands that had 3 "shelves" each shelf was 10 in. circle of glass. I just found wooden plate to replace 1 that got broken at church as we have little ones around. Stands about 30 inches tall & gold colored metal & each shelf goes off from 1 center peice & at 3 heights. Used for flowrers in entrys of buildings or in office for touch of color. Hard to explain. Sorry! Jan