Your 10" Wen should do fine as a time-saver when waxing, but that's what it's meant for, not correcting paint. It just doesn't have the power. With a PC you can use pads from 4" for aggressive work up to whatever size you want to put on, although most folks would say the practical limit is probably about 6.5" or so. Another advantage of using pads instead of bonnets is that you can a much wider selection of pads for different types of work and preferences. Curved pads, flat pads, ones with special grooves. There's also a full range of firmness and textures.
While at least one member he's burnt paint with a PC, it's a truly rare event and not something you really have to worry about. It's a very safe and forgiving tool. It will bog down before you do damage to your paint if you apply too much pressure unless you really try unless you have something *really* unusual. Also, if you do any woodworking it's also good as a sander. You should be able to get one for under $150 with no problem. Look for either the 7336 or 7424. They're the same tool just with slightly different counterweights. If you choose not to buy one that's fine as well, you'll just have to work a lot harder if you plan on doing paint correction.