40x40 is standard?
what are you putting in the frames, canvas art?
To me, standard is 8x10, 11x14 and 16x20, but I deal in photos mostly.
I love to do my own framing, and I purchase antique frames whenever possible. But that is beacause I deal in vintage photos, both ends can be expensive.
Framing in and of itself can be a horribly expensive thing to do. Depends on what you are framing and how much protection you want/need.
Although I can recommend that some framers will have some dicount frames available which they make from scrapped or extra mouldings. Rarely in such a size.
So, I know I have not answered your question....