Rust normally isn't a reason for replacement. The friction parts of the brakes will normally scrape the rust off. But if they ARE severely rusted then they should be replaced. Wear, warping, and contamination seem more likely reasons for replacement.
I have a 95 Tracer, so it's a clone. And you will likely get hosed. Before I started doing my own brake jobs, it ran about 1000 bucks for a 4 wheel brake job. That included everything. Pads, rotors, calipers, drums, cylinders, and assorted rear springs and such. (Yikes, since if yours is like mine the darn car is only worth about 2k at best) The last time I did my front brakes myself it cost about 150 bucks including new calipers, pads, and rotors.
And a DIY rule of brake repair is never change the parts on just one side. So if they have the brakes apart anyway, both rear cylinders should be replaced, and not just one side. (In my opinion)