There's a beautiful one on eBay right now, but it includes the lock and hardware so it's going to bemore expensive than buyinga barestock. If you did buy it, then you could either sell yourold stockorthe lock & hardwareparts separatelyon eBayto recoup some of your investment.
eBay is the place tosearch for used stocks and muzzle loader parts if you can't find them anywhere else.

Good luck if you decide to bid on it!

http://cgi.ebay.com/Thompson-Center-New-Englander-Stock_W0QQitemZ150262466932QQihZ005QQcategoryZ7394 9QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

Pecotoniamakesreplacement TC stocksbut only for the Hawken & Renegade models, and I'm not sure how easy it would be to bed a New Englander barrel in a Renegade stock.

http://www.longrifles-pr.com/thompsoncenter.shtml