Overall, it is a fair price for a working bike. However, it won't be as nice as your rockhopper so I'd suggest waiting for a Deore LX or better {like a stumpjumper) for around that price.

Note: Considering that it's winter (even in California), I'd consider the price high. Considering this, I'd value it between $50-$75. Come March, $100-$125 to the right person.