I have a custom 7'9" x 27" x 3.75" - 90ltr custom mach1 for sale. Its in perfect condition other than one ding in the bottom that was fixed (see photo). It weighs about 14lbs. Fins are set up as a quad+1 (the center fin is two FCS box, so regular thrusters can be used, with three positions - pretty neat really).
Retail is $1450 on this board. Asking for $700.
Corran