http://www.aliexpress.com/item/PRE-ORDER-free-shippingby-DHL-Fedex-Brushless-3-Axis-Camera-Gimbal-handle-gimbal-Stabilized-Mount-for/903692102.html
i think the price for the motormount+motor was around 150$ you might need some other parts also.
got mine here http://www.getfpv.com/propellers/tiger-15x5-carbon-fiber-props-pair.html
are you mounting them in a t-motor? i still havent found cf prop adapters for the 3515-400kv, does anyknow know who has them in stock?