We'll talk random-orbitals here, as rotary units (even drills with attachments) can easily damage your paint.
Off-the-shelf buffers that you see at your major retailers are basically wax applicators... most run under $80-100. The cheaper ones use bonnets for a variety of purposes. Problem is, they don't have the power for serious defect removal and bonnets aren't ideal as they can easily bunch-up and introduce marring.
Probably the undisputed champ in defect removal is the Porter Cable 7224/7336 series... they've been available in at least two configurations for around $120 and up, and except for the difference in a counterweight and the size of the accessories, they're the same unit. Toss the standard equipment aside and buy a quality hook-and-loop backing plate and pad assortment and you've got something that'll last and cover all of your bases, but you're talking about $200 when all is said and done. While you can get the PC at Lowe's and other hardware retailers, you'll likely have to go online for the backing plate and pads (I like Lake Country, but lots of online shops either sell or private label them); or you can get the whole kit and caboodle online. I've used both
detailersparadise.com and
superiorcarcare.net and have had good service.
I've used a PC with various pads to remove defects (use various pads as you need varying degrees of aggressiveness) with Mothers PowerPolish. It's also great to apply PowerWax. Even with simply Carnauba Cleaner Wax, I've used it to remove permanent marker that kids drew down the side of a neighbor's white truck.
The PC is a good investment if you need defect removal.
For those not looking to invest in a PC but needing defect removal, take the vehicle to an experienced professional detailer (get trusted referrals) perhaps once a year for "service" and then you can maintain it throughout the year from then on.