I second the swamp cooler method. If you keep your house around 68 you don't really even need to put ice in the bucket. Just fill a bucket with some water, sit your fermenter down in it, get a towel wet and wrap the fermenter. The ambient air temp around 68 should keep the fermentation below 80, but the wet towel around the fermenter will aid in keeping it cool in case that temp starts to rise because of the reactions occurring in the fermenter.
But always remember, things are different with every house. I've got a neighbor who just leaves his fermenter in his house with the air temp at 75 and his beers never produce off flavors associated with high fermentation temps, but if do the same, my beer turns out pretty badly.
Just experiment around w everything... And eventually get a ranco dual controller... Best investment I've made.