I believe Dixie Gun Works has a few parts for that old Colt percussion revolver, springs and screws. I don't have a catalogue handy and can't check.
Only about 40,000 of these little revolvers were made, not much of a production run. Parts may be a booger to find but Ebay, Ebang and forthehunt.com may be your best bets.
Also, a company called Wiesner's (spelling?) has a lot of parts for the older guns, though I think they deal mostly in rifle parts. Search the net for them.
I'll be in Hartford, Connecticut in October and hope to visit Sam Colt's grave. You want I should bring a Ouija board and ask him what he did with all the old parts?