I watched craigslist religiously for about a month before I found one for the right price. Got a 10 cu ft that holds 3 - 6.5 gal carboys for $70 used. Not a bad deal, but I had to be patient.
What's your definition of cheap? Sam's club is selling a GE 5 cu. ft. chest freezer for $154.87 brand new.
Don't forget you get a warranty for it and since it is new, it will be much cheaper to operate than some ancient thing you pay $50 to $100 on craigs list. It will make a nice kegerator too.
Go to lowes on sunday afternoon or evening when the employees dont want to put the clearance crap away. It was a couple years ago, but I always made the best deals on sunday evening.
I was a dept mgr, and zone mgr..
Sunday evening, about 2 hrs before they close-ASK to speak to a MGR. Not the people on the floor.
craigslist, and be patient. You can get freebies if I didn't have to work i could have picked up 3 in the last month and a half. Use the rss feed button, and create a feed for chest freezer in your local area.