I think that mapleleaftickets.com are cheaper by a bit. do you subscribe to the Mousesavers newsletter? There is a link in their monthly email with a discount for under cover tourist.
Try AAA if you are a member. I priced AAA vs UCT and they were cheaper. They do charge for shipping but if you have an office in your area you can pick them up with no charge.
No offense, but there have been many horror stories on here from people who have purchased tickets from Craigslist or Ebay. I would avoid them if all possible.
I agree with UT. I've yet to find them cheaper any where other than. I'll have to check Mapleleaf.