I recently picked up a discontinued utility sink complete with legs and faucet for about $30 at the local Big Box. It's around 2X2X1.5 Feet. I don't think you'll have much success draining into the wash drain without a pump though. The water has to be lifted around two feet to get to the drain. The five gallon bucket with a fountain pump should work but probably wont keep up if you're trying to wash with a constant flow.
What about finding a sump pump on craigslist? just set it in the bottom of the sink & let it run.
I use an upside down plastic milk crate to set a dishwash tub on. You could put a sump pump under a milk crate.