On that one, I would advise watching Craigslist... you can find cheap or free fridges on there all the time. That, or let your family and friends know that you are looking for one. Sooner or later, one of them will remodel their kitchen. That is how I scored mine. You will not regret having a dedicated beer fridge around.
The seattle area listings, as an example, currently have four free fridges that are in working order.
I use my Yooper Lagerator. It's an Icecube cooler, with a new lid made of styrofoam so that the airlock peeks through. (See my gallery for pictures). I could have used the old lid, but it wasn't insulated, and I can just put on the regular lid if I want to use it as a cooler.
I put the carboy in, then put water in it. Then, I add a couple of frozen water bottles and keep it in the basement. Changing water bottles every three days in the winter keeps it at 34 degrees as long as I want. I can lager in this for 6 weeks or more. In the summer, I can change the water bottles daily and keep it in the low 40s.