what vin*tone says. Buying a bass parts per parts will set you back more than buying a complete bass. The best chance of finding parts and not paying top-dollar is registering at fora like offsetguitars.com and shortscale.org, and hope for the best. They have a vivid marketplace with spare parts that go for less than their ebay counterparts. Biggest issue will be finding the bridge and the correct, short-stemmed lollipop tuners (only used by the Coronado & Mustang, stock Fender-tuners as used on the P & J won't fit). A Coronado guitar-body CAN be modified to accept a bass-neck, by rerouting the neckpocket.
The 250USD for the complete wiring-tree is fairly cheap, a friend of mine bought 2 pickups for that price, excluding the pots. They are rare and seldom found (only the Coronado used them, and the leftover stock was sold by Fender to H.S.Anderson).
Apart from that: quirky little basses, can sound funky, I like them: http://www.youtube.com/watch?v=MLFsanW1D-s