You probably want to check out http://www.framesbymail.com

They've got lots of different styles of frames and mattes (you may want to purchase your matte in person though, for color matching purposes), and their prices are WAY below what you'd normally pay. I know that they sell polycarbonate, but I'm not sure about glass. If they don't, you'd have to get some glass cut somewhere else, but shopping here will still save you a lot of money.