If you ARE going to make the effort, and it is considerable, you should really investigate the cause of the rust in the = first place. A scratch? No problem, sand, prime, repaint. = Paint worn away by grit, etc.? Again, no problem; maybe add a layer of = undercoating before the topcoat. But, a rust perforation from standing water = will recur, unless you replace the rusted metal with a non-corroding substitute. And little body rust flecks are usually due to = deteriorating paint: little holes you can't really see, even up close, with the naked = eye, but are plenty big enough for the water to reach bare metal, start = corrosion, and travel along the soluble rust, furthering the 'cancer'. The only = real answer here is the total repaint, and I mean TOTAL, if the cancer is widespread. That's ALL the body, sanded down to the metal, = inspected for corrosion, repaired, primed, painted. $3500 - $4500 is very = realistic for this size of job; if it really is a good shop, you're getting a deal.

But for little jobs, beware: it can get = messy. Have you a wind-free place to paint? If not, overspray can dull other = car parts; masking the whole vehicle to paint a small fender patch isn't = unheard of. Are you prepared to use proper acrylic enamel paint? = That means mixing, hardeners, other additives; again, messy. Has the rest of = the vehicle's paint job oxidized, even a little? If so, you can make a = 'perfect' match to its paint, and the freshly painted patches will stand = out like a sore thumb.