I'm in the market for the same seat. Trying to mount it on a CB750 though and Motolanna only makes that for Yamaha's I believe.
Lemme know if you find it for $150 cause I'm on the same hunt with the same budget! haha. Motolanna will charge you $100 in shipping I believe. Closest I've found was in the link below from dime city cycles. As far as the reviews go, it's an incredible seat, but a b*tch to put on...good luck!
http://www.dimecitycycles.com/vintage-cafe-racer-caferacer-chassis-seat-parts-black-dcc-originals-ribbed-leather-wrapped-one-up-racing-seat-dcc-lwrapcafe-r.html