I use both namecheap and namesecure.com. They are both in the under $10 a year range, though namesecure I don't believe offers free forwarding for mail anymore.

It's as simple as just going in and filling out a form after you select the name you want (assuming it's available) and then telling it where to send the mail once they get it set up for you.

godaddy is in that price range too, and gives you 100 different forwarding addresses at your domain for free too.