A couple months ago I decided to try an experiment: switching from Gillette Mach 3 razor blades ($15 for a 3-pack) to cheap, one-blade Bic razors ($2.50 for a 10-pack).
The results were about what I expected. The three-bladed razor is much nicer on the skin. It shaves better, easier, and quicker. The one-blade razors scrape my skin much more easily, leaving cuts behind. However, the problems seem to be diminishing, perhaps as my skin gets more used to the rougher shave. I was seriously considering switching back for the first few weeks, but now I'm going to try it for a while longer. Over time, it's a pretty significant cost savings, at the expense of a little bit of the environment and a little of my comfort.