I read an article some time ago about a guy that had been using the same disposable razor for a year. He stated that drying it was the key to making it last longer. I’ve been drying mine ever since, but I still only seem to get about 2 weeks out of a Gillette Mach3 cartridge before it starts getting uncomfortable.
Costco is currently selling a package of 52 very good quality disposable razors for under $30. That would get me through about three years. My wife picked up one of the newer Shick platinum razors. Blades are expensive and don’t last any longer than a good disposable.