Sure you could do it yourself, but why not visit DrSnip.com before deciding? [update: after all, he's cut such famous vas deferens as The Zero Boss's. Check out the firsthand account from Jay's book.]
Dr Snip Vasectomy Knife [finkbuilt.com, via boingboing]
Dude! That's the guy who did my vasectomy! He's in my book!
[Gee, thanks for sharing (sic), I totally want one of those. A pocket clipper, I mean. -ed.]