Hi, I think that $300 would be a fair price.
Bridgestone CB-0 Zip Bridgestone CB-0 Zip
bike bike
1990 Bridgestone CB-0 Zip Bike in excellent condition for sale.  This model was the predecessor to the cult status XO series.  Recently restored by Cosmic Bikes.  New parts include: rear wheel, dirt drop stem, Aherne MAP bars, MKS pedals.  Black color in 50cm (center to top).  Perfect for 5'4" to 5'7" with 29-30 inch stand over height. 1990 Bridgestone CB-0 Zip Bike in excellent condition for sale.  This model was the predecessor to the cult status XO series.  Recently restored by Cosmic Bikes.  New parts include: rear wheel, dirt drop stem, Aherne MAP bars, MKS pedals.  Black color in 50cm (center to top).  Perfect for 5'4" to 5'7" with 29-30 inch stand over height.