http://www.havlinsales.com/
Click on the "bolt action shotgun parts" tab and scroll all the way to the bottom
$27.00 each.
Caveat is though that they are not always in stock. Vic and Cheryl Havlin are good folks to deal with though. Email them or give them a call (contact info at their website) and they may have them in stock.
Could also try e-gunparts.com