they are from a private mint, not the US Mint, commemorating the Bicentennial of the US Constitution. If you like them, they're worth the $5.
This link has a little bit more information about these coins: http://coinquest.com/cgi-bin/cq/coins?main_coin=15646 Coin Quest considers them tokens and it concludes: "A dealer might pay as much as $2 for a nice-looking example." I did see the Madison token selling on e-bay for $8 alone, so who knows? Either way, $5 sounds like a potentially decent price for that set.
