It's called a Gerber LMF (for "Light Multi-Function"), and it dates to the late-70s or (more likely) early- to mid-80s. It wasn't a ridiculously expensive knife at the time, and hasn't held its value as well as some of the other knives Gerber was making at the same time (like its big brother, the BMF ("Basic Multi-Function"). I tend to avoid placing values on things, especially right now with the economy as screwed-up as it is, so I'll leave that for some other brave soul.
Nice knife, by the way. I came this close to buying one way back when. And I l-o-v-e the handle.