I would suggest waiting until you have completed the project. Then, you can audition different size frames. I've had luck picking up inexpensive frames at thrift stores.

I wouldn't pick a frame until you finish the project. I use coupons and go to Michaels. If it is a standard size you might find a frame per cut. If you have never framed a piece take it to a professional. It is too much time to waste on a poor framing job.