Like I was saying above, I have found a place that will cut any size opening in a mat that fits in a standard frame size and they do it at a really good price if you buy in bulk of 12. Even their single purchase mat prices are really good and hard to beat.

The place I have found is called matboardhq.com and I ordered a bulk, sale of 16x20 mats with a 10x14 opening. ended up with shipping to be about 4.50 each cut mat.

 

They even carry a whole kit of the mat, clear plastic, and a backer board or just the clear plastic envelopes to put your standard mat in and yes they also have a simple black frame style. 
I haven't purchased any of the frames they offer but the prices seem very reasonable but the thing is they only seem to carry one frame style which is a simple black frame.

I also posted below about a great matting deal with Amazon. 

The most important thing to remember if you want to save money on matting and framing your watercolors is to paint to that standard size mat opening because custom framing is when matting and framing get really expensive. If your painting larger pieces that go over the mat size of 16 x 20 it will also get more expensive because a full matboard size (32x40) cuts down to 4-16x20 mats. If you go over a 16x20 mat then the price is for the half or whole price of the full large mat.

I recommend if you really want to save money is to buy the matting and framing in bulk first and paint to fit into those sizes.

If you know of any places physical or online that do great and reasonably priced matting and framing please let me know and email me at beckerart@gmail.com so I can pass it on to others.

Thanks