I don't think you're going to find any/many deals for the MK ticket, plus they just raised their rates. I believe it's now $100, maybe a bit more, for a one day non-park hopping ticket. None of the discounters carry the 1 days, of if they do, it's at full price.

I'm not sure about universal tickets. I have seen multi-day tickets at Costco at a discount, but not lately.