What I do when I want a low cost (but still reasonable) solution is to buy a cheap frame with a pre-cut mat from Walmart/Ikea/etc.. and just mount the image in that. Of course, you have be careful about what frame you pick- ideally you want something that simple looking, but not cheap looking. The other thing you have to watch out for is that you can only get "standard" sizes for precut mats, so if your picture doesn't have a 5:4 (for an 8x10, 11x14, 16x20) aspect ratio, you will have to crop.
Cutting your own mats is a good solution to this (I'm starting to get into this), but it will take some practice to do a good job (so be prepared to spend some time on this). Making your own frames is also a good low-cost solution, but takes even more patience to do well, especially if you're not already familiar with wood working tools and finishing. I'd avoid custom framing- it is far too expensive.
Of course, going with a frameless solution as others have suggested is probably the least work of all.
Yes, I get your point. I was off on this mission about around 2005. The plan was to buy inexpensive manufactured frames (e.g., Aaron Bros, Ikea, Michael's, etc.) and custom-cut my own mattes. Mainly because the problem was that Aaron Bros. tended to carry very little stock in "plain white" pre-cut mattes in standard "photographic" dimensions (11" x 14" and 16" x 20" sizes). I also had the added problem of shooting in non-standard aspect ratios (1.78:1 or 1:85:1).
I started to buy some rotary cutting boards and graphic arts supplies (some of which I already had), but then of course, I got distracted and gave up. Now, I no longer have a dedicated "matte-cutting" work space, so I'm back to square one again. I'll probably go the black Foamcore and canvas print route. Until we finish remodeling, I can't hang any artwork up yet anyway.
But certainly, if anyone finds an inexpensive supplier for pre-cut photographic mattes, online or retail, I'm all ears!