Do a search on "chest freezer" and you should come up with some results which meet your needs. For serving purposes, you can construct a wood collar and attach the lid to the collar and the collar to the top of the freezer, then insulate. This way you can drill for taps directly into the collar and dispense from the freezer. Or, if the freezer is tall enough, you could just go the cobra head route and save some work. I don't recommend drilling through the freezer itself however unless you are 100% positive there are no cooling lines running through the spot you've chosen.
Check you local Craigslist for chest freezers, usually there are a variety and many times people are getting rid of them at no cost. A larger one in the 15-20 cubic foot range can hold a dozen corny kegs or you can mix and match kegs and fermenters. Your temp controller should work on it as well. There's no reason why you couldn't lager in the freezer during the summer while simultaneously serving from it if it was large enough. Good luck!