Last December I ran out of razor blades. I went to the dollar store and bought a package of 8 disposable razors for, you guessed it, $1. I used the first one for 3 months. I am now one month into the second one and it is still sharp. So I am on a pace to spend $1 every 2 years on razors.
They aren't the best shave I ever had but certainly good enough. Of course, I would never use them to shave my mustache!