Prices for 2nd Gens are all over the place. If you can get a lightly used or unfired 1851 Navy for $350 - $400, you'll be doing good.
Always make MO smoke !
Get to know your dealers. Here in the UK I found one dealer, one of the biggest over here, who is convinced that all 2nd. & 3rd. generation percussion colts are re badged Italian guns and buys then in on that basis. I have talked him into letting me know each time he gets one. It's a great arrangement, he thinks they are Italian and buys them on that basis, I get to know and pay him on that basis.