I am not sure where to put this question, so this group wins . . . or loses : )

We just recently started producing canvas prints, to our surprise the frames for these are one of our biggest expenses. We want to make our own frames but not sure what kind of wood to use. We tried plain pine and it warps, anyone . . . any suggestions? They are just strips of wood with a few angles and holes put into them? Any suggestions on the type of wood is much appreciated, not wanting to use MDF.

Thanks,
Zelma