Find a Target with a Clearance end-cap. Gillette comes out with a "new" Mach 3 every six months or so, and Target clears out its inventory.
I got one for free on a $2.00 can of Gillette shaving gel.
Buy the replacement blades at Walgreen's or Eckerd when they're on sale, or buy the Personna 3-blade replacements at Wal-Mart.
They're about half the price of the Gillette blades, and are likely made by Gillette or Schick as private labels.
Sorry. That's more than you wanted to know about Mach-3 razors.
Also, a man doesn't know what he's missing if he's not using a brush and shaving soap.