A nice paint job like that for a grand is not bad, but you can tell they make their money by doing a minimum amount of masking work, and I would guess they also make their money by doing a minimum amount of prep - like cleaning and scuffing. Probably have some peeling in short order, but pretty out the door.
The linked bus is nice. Looks like minimal rust. DT466e is a good engine and the 2000-series transmissions are good, too (I have both in my bus). If you're going to go check it out, buy a Bluefire first - this is a gadget that lets you connect a tablet or smartphone to the engine and read the dashboard data and a whole lot more, like the engine's true mileage etc. A Bluefire is a great investment just for bus shopping, and you can eventually use it in your actual bus to give you a digital dashboard (and you may get a shocker like I did when I found out my transmission temperature gauge on the dashboard was completely inoperative, not good).
$7.5K seems like a lot but I guess that's the deal these days. My bus cost half that - but then I spent more than a year repairing and rebuilding rust damage. The fact that it's actually like $7,499 or whatever suggests there's wiggle room on the price. The seller got it for a lot less than that.
Edit: if you can, find out what the bus' rear gear ratio is, since that will determine how fast you can go on the highway. My bus has an atrocious 6.17, so the bus maxes out at 63 mph and is really limited to 55 mph on the highway to keep the RPMs around 1800. Good ratios are in the low 4s.