Update: Sold! Craigslist is the best.
I bought a new PowerBook G4 15″. I took out the 512MB chip and replaced it with two 1GB chips. This chip is lonely and wants to snuggle up in your PowerBook. These go for $56 plus shipping at OWC (macsales.com). I’ll pay for shipping, too.
The chip label: Samsung 512MB 2Rx16 PC2-4200S-444-12-A3