When I polished my boat, I was too cheap to buy one of the better polishers around and went to Harbor Freight and got their polisher. The darn thing worked great with no problems. When I started the project, I also knew nothing about what I was doing and was hesitant to invest too much money in case it didn't work out. In hindsight, just about anyone can do this and I would have purchased one of the better machines as I am likely to be doing this again.
The more important part is to get good wool buffing bonnets and wash them often.