I'm sure folks here have me beat in riding experience. I am well versed in cheap bikes.
Cheap bike usually isn't. Cheap bikes need repairs pretty much always. If nothing else, there is guaranteed to be neglected maintenance.
Mileage doesn't matter. Bikes die from sitting more than they get worn out. Gas turns to sludge, rubber hardens, rust creeps in. Figure on $3-400 to recommission an old bike. You might luck out with less, but don't expect it.
"It runs fine" and "needs nothing" are from the same book as "check is in the mail". Even if the seller is not out to purposely screw you, they almost always don't know as much as they think. "Ran fine when parked" is quite hilarious.
Check tires. They can look good, but be ancient, and not particularly safe. "New tires x years ago" are not new.
Mechanics to work on old bikes are hard to find. Better be willing to learn to do what you need to do.
Not all brands are equal in parts availability, or even information. Yamaha parts listings are available online all the way back to 1970's, or even earlier. Kawasaki... not so much.
My first functional bike was an XS400. I am 200-210 pounds, depending on how close I am to a holiday. I ran that thing all over town. 60-70 mph on the highway was perfectly doable. Long trips on something like that aren't great, though.
Bikes that are supposed to have fairings and don't are almost always the result of someone wrecking and not replacing the plastic, not a "street fighter mod" as they always say in the ads.
I'm going to be looking to sell my FJ1200 as a "streetfighter project" soon. It's the one I crashed last year... :)
One thing to be aware of is that having a shop do the maintenance is expensive, but you'll want a lift to do it yourself.
A lift? Must be a cruiser thing. I've done everything using the bike's own center stand, including taking off front and back wheels.
