I'm not saying that you won't be successful in that endeavor, but there are better paths to your goal. Bingham's is the place where most bowyers get their start. They have everything you need to get started in bow building, including kits that supply blue prints and materials. They have DVD's that are great for first time bowyers, and walk you through all of the steps to building a glass backed bow.
But if you are set on your plan, then Old Master Crafters (OMCbowyersupply.com) carries green and I believe brown glass. Bingham's also carries brown glass. You might also check with Big Jim's (a TG sponsor).