Have you checked out prices at framing stores lately? Since I didn't want to pay $250 for a frame, I decided to make one out of some spare 1x4 Douglas Fir that I had. It's a single board with a router cut at the edge for detailing. I routed a rabbet onto the back, and kreg-jigged it together. I distressed the wood by beating it with a hammer and chain.
Prior to completing the frame, I took a sample piece to the framing store (who would be matting it) to make sure they could work with my rabbet size. I ended up having to make it deeper and wider to accommodate them, so I would advise doing this if you're taking it to a framer.
I never dreamed I could actually make a frame, much less a piece of furniture. Thanks so much to Ana for sparking all of this. I've found my creative calling thanks to her!