We're currently working through predictive market problems but are on the front edge of the process. So far we've talked to a couple of sources. Media Predict, and Inkling Markets. Media Predict (mediapredict.com). We've also had discussions with Inkling Markets (inklingmarkets.com) which is the platform that Media Predict uses. Inkling has a remarkably easy way to set up markets and we're investigating test markets there currently.
There was another consultant we interviewed about a year ago but I'd have to dig through old email to find it.