If you're planning on doing anything production (ie more than one off) try looking at something like the logan 450-1. Otherwise you can get by with one of their straightedges (adapt-a-rule) and cutters for around $50-75.
I have the Logan 424-1 and it works fine for me. I think I paid $50 for it brand new with a box of 50 extra blades. I started cutting my own mats because I shoot 6x6 and it can be difficult to find square mats in various sizes. Actually, I just recently did a run of 30+ matted and dry mounted silver gelatin prints and this setup performed beautifully. I have very limited work space and simply couldn't accommodate the size or cost of a more sophisticated machine.
I have the Logan 450-1 and paid about 150 zops for it on Amazon. Sure, it is a tad more expensive, but you get some very worthwhile features with it. Accuracy of cut is all but assured with this machine. The inside bevel cut is a breeze. I've had the lower cost Logan mat cutters and I can tell you, the extra $50 is well worth it. If you figure that you will eliminate mat board waste with incorrect cuts, you'll save significant change per year.