52,000 miles isn't too bad for a '91, just broken in wit ha lot of life left. The cosmetics are rough, but fixable. +1 on liking the RS fairing. Looks like a nice winter project bike.
Figure on doing the brake pads, lines, and possibly the rear master cylinder(at the low point in the system water collects there and corrodes the bore). All the fluids need to be changed and the clutch and final drive splines need to be lubed. It's a good idea to replace the rubber bits around the engine if they look dry and cracked.
With 52K on the clock chances are good it has been run enough to not have been neglected. Still, you want to plan on cleaning the fuel tank and replacing the fuel filter. While looking at the tank, check the seams at the bottom for signs of corrosion and leaks.
Can't tell from the photos, but if it still has the original shock, figure it will have to be replaced sometime as it has a lot of miles on it.
Check the shifter for freeplay. Should be nice and positive with no floppiness. If there is, you will need to go into the transmission to tighten the grub screw on the shift mechanism. Doable in the driveway(I did mine there) but takes about a weekend and can be a bit nervewracking at times. Would make a good point for getting the price down a little further, but at $1k it may already be priced in..
All in all, it looks like a fair deal as long as the engine runs well and the transmission goes through the gears properly. If you do the work yourself and shop carefully for parts there is no reason you can't have a pretty nice, reliable bike next summer for well under $2000.
