I fixed blade carry occasionally, depending on where I'm going.
Some cities ban all fixed blade knives, some ban knives over 3.5". It's really important to know your regions laws on this subject as well as other regions you frequent.
My regular choice is either my KaBar TDI or my ESEE Izula.
The TDI is carried between my belt and pants.
My Izula rides in a custom pocket sheath I made
It rides perfectly and is easy to deploy.
Of course, neither of those are "cheap", though...
The Spyderco Ladybug and Manbug definitely belong on this list. They are ridiculously useful for their size. (Sal Gloesser, the company's founder, carries those more than anything else in their catalog.)
Kershaw is a great option in that price range, and don't forget SAKs.
If you're into traditional folders like me, the Buck 300 series (still made in the USA) is solid, as is the old reliable Buck 110. If you shop around, you can find some Case knives for right around $50. Their yellow Sodbuster Jr. Is on the shelf at Lowe's for about $35, I think, and it's one of the more consistently solid knives in their line-up. Just be sure to inspect Case knives in person. I love them, but their quality has been inconsistent for a while now. If you order one, there's about a 50% chance you'll have issues with proud springs, wide spring gaps, blade centering, walk and talk, or blade play.
As far as fixed blades go, you will never get a better knife for the money than with a Mora.