The low cost Ka bar dozier lockback mentioned above is very high quality for the price. I think it's at least as good as lockback spydercos which cost more than twice as much. And the thumb stud can be reversed if you're left-handed (like me).

Also, it comes in a variety of blade styles, including a drop point which has a hole for opening, rather than a thumb stud.

I'm sure there are better "survival" folders out there, but as you can tell, I like mine a lot.