Too true!
A buddy of mine build one out of a metal bandaid box, a couple of magnets, and a coil of wire. It was sensative enought to pick up people walking in the house (he had it burried in the yard outside his window), and trucks on the busy street nearby. He spent about $.05 on the box and about 10 bucks on the analog/digital converter hookup into his computer. (circa 1987)
Yeah, I think NBC News led off last night with "The quake was picked up in CENTRAL PARK NEW YORK! WOW!" as if that was a big deal.
There's actually a mailing list, PSN-L, for people that build their own seismometers. Most of them end up spending a bit more than your friend, buy old sensors off e-bay, and dig a hole in their backyard and pour some concrete to anchor it in.
I used to subscribe to the list so I could be the ABSOLUTE first to hear about big quakes (faster than FR, faster than NEIC, faster than CNN) but to get that I had to put up with several dozen e-mails a day about how to build the seismometers, which I really am not interested in.
Problem is with one seismometer all you can do is tell how far a quake is from you and how big it is (roughly) not where it is. It's pretty amazing though, through a series of e-mails the people on the list tend to get it figured out pretty fast.