Hi Nite Fenix
Our mint site is at
http://www.usmint.gov/mint_programs/
For a few years we were getting the mint sets when they came out. (My son was putting them in a drawer).
The difference is the triple polished dies that they are stamped from. They really are perfect.
For a long while a year set would cost 11.00 but now the price is through the roof. Something between 22 and 23.
Over the years, there have been coins minted in differnet cities. Currently, Denver and Philadelphia make the coins for circulation. The San Francisco mint makes the proof coins and on some occasions there are a few made in West Point (Near NYC). The W mint mark was only for like one year.