The last brooder I built was designed to have a wire bottom where all the water waste would fall into pans below. I recently took on a part time job at Lowes in the garden center, and since we're not busy yet I have a lot of time to cruise the store looking for ideas.
Found a shower base on clearance and it got me thinking.
These shower bases average 32x32 or bigger. Just the pan that goes on the floor of a stand-up shower. Has this handy hole in the middle. Drains towards the hole. Way easy to clean. Good height on the edge.
So I was thinking I would make a 10x10in wire covered "stand" for the waterer, to go over that hole. Attach a short length of pipe into the hole. Build around the tray the rest of it, using 2x2's and hardware cloth. Front door, top door.
Legs would be a little taller than a 5 gallon bucket. Insert 5 gallon bucket under drain hole. Ta-da!
Empty the bucket as needed. Hose off the whole thing. Easy to sanitize between uses. I think I can get it built for less than $150.