Emerson makes the CQC-14 for this very reason; it's got a full length handle but a short blade, to be legal. New, it's out of the price range you quoted. Used, however, it may be just a little more.
While Emersons run a couple hundred dollars in many cases, they can be had frequently on ebay or the classifieds here and elsewhere, for a lot less. I seldom pay more than a hundred or so for Emerson knives, and I've bought quite a few of them. In fact, I have a wall in a safe lined with with them. It's a compulsion, or sorts.
Are you looking for a blade with which to fight, or a utility blade? A swiss army knife will handle a lot of simple cutting needs, though you probably don't want to go to combat with it (I did...but it mostly stayed in the footlocker).