I'd be willing to bet the calipers are fine. If you change the caliper bolts (only a few bucks at Strauss or any real auto parts store), then change the O-rings and lube the slide pins that the calipers float on, you should be able to get away with just changing the pads and rotors.
The only tough part will be getting those bolts out if they're that frozen. WD-40 and a large breaker bar will be your friends.
