Good Lawn Mower Model?

I am looking for a good riding lawn mower for sale - used or new...just has to run well and not break the bank.  I see ads for bobcats for sale but not a lot of riding lawn mowers.  What is a good name and model? Right now, we pay somebody to cut our lawn and I think it'd save us money in the long run just to do it ourselves.  It's getting expensive - especially with gas prices going up so high.  The lawn prices keep going up.