You can get an old school safety razor for under $20 and it will last forever. They are what double sided razor blades (the kind you normally see used in movies to split cocaine) were designed to fit into. Good razor blades can be found at a rate of about $0.05-$0.10 per, and last about 4-5 shaves - for me at least - before they start going dull and pulling. They also get me as clean of a shave as any other razor
Still not sure why people pay 10x more on cartridge systems, but maybe I'm just weird