Love, love, love my roomba! I just got a new one for a great price at Costco.
My old one last 3 years on one battery. New battery was about $60 with coupon so $20 a year, but right after I got the new battery the brushes stopped turning so a new one was needed. I don't have any carpets so I think that makes it easier on the machine. If anyone comes out with a machine that will clean itself, that will be the one to buy!
I've never checked out the mint.