I keep a couple of straight razors and a Gillette TTO Speed Tech. The straight razors are great if you need a really precise line and such. They are delicate, and require a decent amount of maintenance.
The old Twist To Open type do a nice job, and are cheap as far as blades go. The most important thing I've found is just to tighten them down realistically tight, and replace the blades when they slow down and require to much pull to cut.
Merkur, Parker, and Jagger make fine examples in the $25 - 50 range. Older Gillettes are usually in the $10 -100 depending on luck, condition and collectibility.
I just use the Personna (100/$ 15) blades, you can buy fancier blades, but I've never noticed anything better about them.