Durable folders with secure locks in your price range:
Benchmade Griptillian
Buck 110
Many from Kershaw
A few from Spyderco
AG Russell Featherlite
Seems to me you simply need to browse the selection at a couple of major knife retailers, pick out a few that interest you aesthetically and offer a blade shape and steel that suits you, then search the forum for reviews of those knives.
Good Luck!
-Bob