You guys make it sound like a Carlsbad Masi is a bad thing - pristine ones bring as much (sometimes more) than the equivalent Italian ones. The most valuable ones arise from the Pre-California era, of course. I think an early 80's Masi will have some worth, although condition will set the price more than anything. A replacement fork is really gonna drive the price down. Finding an original one is tough to, like, impossible. You could probably find someone who would build a replacement, but the cost is gonna be significant.

Shimano parts will drive the price down as well, although an early dura ace or 600 arabesque group also has worth in its own right.

All of that said, the demand for this manufacturer is high enough that people will queue up to buy a beater. If you can afford some time to wait with the seller, post a picture and there are people here who can give you a good figure for a redo on it. That'll give you a good idea what the starting price should be. Otherwise, I think $100 is a really good deal for any masi, $200-250 is probably what most people would expect to pay for Masi bones.