I would check to be sure it still has the thin grip mounts, then call Colt first. They will not be on their web site. Call them and talk with them. Also interested what you consider a great price on one is.
As mentioned by dsk, Altamont has been reported to have made the original grips.
I have been impressed, in the past, with their customer service and fast turnaround time, including times when grips are not in stock and they have to make a set.
Altamont's pricing is usually far more favorable, than found anywhere else, including, ebay.