I was in Costco the other day and they had "bulk" cartridges (3 blade, 5 blade, light saber blade, yada, yada, yada) for a couple brands of razors. HOLY COW are those things expensive:Q.
Some of them were >$2 each (16 pack for $32+). Right next to them they had a 52 pack of Gillette twin blade disposables for ~$14 or so.
Based on the above, I'll take the "free" razor but doubt I'll ever buy a replacement blade for it since they cost so much.
I do recall seeing a tv show on the Discovery Channel where they took a disposable razor and put it into the "deep freeze" process at like 320 deg. below zero and then slowly returned the razor to normal temps. Apparently, the atoms in the razor get "perfectly" aligned and the host of the show claimed he'd used the razor for some long time period (e.g., 7 weeks) and the razor was still going strong (i.e., wasn't dull yet). Or course it most likely cost a small fortune to cool the razor, but it was a "cool" show none the less