There are 11 starting players on Offense and Defense. I think it varies how many players are actually on the roster. It also depends when in the season we are talking about. In preseason, there are more than during the actual season.
Current Number of Players on NFL Roster 32 teams x 53-man roster = 1,696 players When its not regular/post season, teams are allowed to have 80 men...Not all teams carry the maximum. 80 x 32 = 2,560 players during the off-season/pre-season.
Your local card store will have basic land cards that you can purchase or trade, they may even give you some depending on how many you need. Many, many online stores can sell you basic land cards. Other players may have spare land cards that they can part with.