I've owned 3, and own the 3rd one now. I'm in the process of replacing the water pump seal now, and I did on the 1st one years ago, too. Not hard, but the engine DOES need to come out, but even that only takes a little while and it's a one-man job. Knock-on-wood, but I've never had a stator issue, but early ones did, and early ones had a gimpy camchain tensioner, IIRC. And, they seem geared way too short for a 500cc bike. 4500 rpm at 50 mph. I keep reaching for another gear...
The water pump is on the rear of the motor, right between the V and it has a tell-tale weep hole that drains to the left. And, since anti-freeze can damage paint, look for discolored or wrinkled silver paint on the engine down the left side. That'll let you know if it's seen leaks. Otherwise, check the oil, listen for taps / knocks, etc. etc.
But, other than that, they're fine enough bikes. Plenty of power, nice sound, liquid-cooled at a time when not many others were, shaft drive, very smooth motor. Mine consistently gets 55 mpg. Not particularly sporty, but more like a light sport-tourer. Other than the 2 problems (seal & stator), they're very reliable, and according to some, very long-lived. Maintenance is super easy - oil filter is right out front for easy access. Air filter pops right out from under the seat. Battery is right under the plastic side cover. All consumables are readily available from online parts houses, including ebay - battery, brake pads & shoes, oil filter, air filter, plugs, etc. Valves are screw-and-locknut adjusters, so that takes only a few minutes, and the cylinders poke right out at you for easy access. Of course, shaft drive so no chain maintenance at all.
I don't know about where YOU live, but $3000??! That's DOUBLE what a clean, low-mileage bike around here (Orlando, FL) would go for, and we seem to be pricier than most places in the US. Must be our year-round riding weather.
Good luck with it.
Kirk