Was in the Wally World here in The Woodlands and the 48qt Cube without the wheels is on clearance for $13. Figure if they are clearing them out here they might be elsewhere.
I picked one up before Christmas, it was just shy of 15.
Look them over though- some had drains, but most did not.
Not a huge deal, but one less step if you don't have to drill your own.
I did the exact same thing, I think I spent about an hour in Lowe's trying to come up with the right combination of parts. My friend and I assembled it in the parking lot to make sure everything fit before we left.
I picked up a 48qt rubbermaid cooler for 17 bucks at wally world. Very nice except that the spout goes thru the insulation so I needed a more parts to make my mash tun.