I feign brushing back my hair in the hope of hiding the crackle of insults spewing from my earpiece. For 45 minutes, I've been doing the new-boat buying tango with not one partner, but two-the sales guy in the showroom, and the one barking in my ear, a 15-year pro whom I've assigned the task of getting me through this in one financial piece. Thanks to the miracles of hidden microphones and videocameras, earpieces that would make the Secret Service proud, and an unmarked van in the dealer's lot that has half the inventory of Circuit City, my undercover pro has been coaching me in how to get the best deal possible. He tells me just what-and what not-to say. I'm like a ventriloquist's dummy; I open my mouth, but it's his words that come out.