Maybe I do not understand what you are asking. When you say "brake drum cylinders", I am thinking of the wheel cylinders in the rear. You can pick up the wheel cylinder hone (goes on a hand drill or such) and rebuild kits for probably less than $20.
I wouldn't even bother rebuilding them, just pick up some new or rebuilt ones from a parts store. They are usually cheap enough to make it not worth the bother of rebuilding your own. Much quicker and if you put them in and they leak, you can take them back. As far as changing them, do yourself a huge favor and buy a shop manual (Haynes or Chiltons) and read. They usually do a good job of explaining how to work on brake systems. They are not very complicated to repair and you can save a ton of money doing it yourself.
I'd say that 3hrs labor is reasonable for the job. At $80+/hr for labor, plus parts, plus brake fluid, it could come to ~$300.
You MUST use flare wrenches to remove the fittings. Being in VA, you MAY not have much problem. For people in snow states, if the expect to be able to effortlessly remove a brake fitting on a 15+ year old car, they are on crack! I'd say that, for snow states, there would be a 10%-25% chance that the brake line would be rusted to the fitting on the rear and that the wheel cylinder couldn't be removed without breaking the brake line.
Replacing a rear cylinder is one of the very VERY VERY few places you can even think of using heat on a brake line. Just make sure that you do a good flush. Either use the two man method (free), or get a pressure bleeder ($50). See my brake page on info and articles on bleeding brakes.
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