redi-mat makes 8x12, my local lab carries them, as well as 12x16 frames & also ready made frames with pre-cut mattes (I'll check the brand on the ready-made frames for 8x12). ACMoore & those type of stores are consumer oriented... which is why consumers want 8x10, and then can't figure out why 2" is "missing" from the shot, ha ha!
Living in a fish eye lens.... Caught in the camera eye....