I purchased this seat base two years ago, did the requisite modifications, added seat foam, bumpers, stainless hardware, etc…total cost was ~$175USD ($100 for seat base, $65 for KF Freeride Seat, $10 for hardware) since it takes two seats to make one, then there’s the hours of work required to make it functional…
I used the seat for muni, no trials, no abuse, seat base is in excellent condition, can be sold with or without the cover. Cover is not shown, it is the new style KH Freeride Green with breathable fabric top.
I’m selling the seat for $75 plus shipping, the cover is an additionall $10 (new it is $19). Send me a PM to discuss payment, shipping, and to ask questions.
I closed the thread to prevent “clutter”, so send a PM 
Here’s the seat base as sold new by UDC: http://www.unicycle.com/unicycle-hardware/saddles-and-accessories/gemcrest-carbon-fiber-seat-frame.html/
Here’s mine, shown without a cover:
