I bought a Gerber Chameleon at my local Target dept store, walmart sells them too, for around $25 which included a belt holster as well. Lockback, thumb stud for quick opening, and a thumb hole for securely holding it when opening. I love mine though I wish it weren't serrated.
A lot of knife for a little money. It's both a work and self defense tool for me, and I'm very happy with it.