(http://buzzer-manager.com/)Log-in there to see flag chasing stats. It keeps track of number of teams in each country so that would tell you "rare".
27 Nations have 10 or less teams.
#1 Pakistan Pakistan 1
#2 Misr Misr 1
#3 Hayastan Hayastan 2
#4 Rep. Dominicana Rep. Dominicana 2
#5 Al Jazair Al Jazair 2
#6 Ghana Ghana 3
#7 Lubnan Lubnan 3
#8 Tounes Tounes 4
#9 Kazakhstan Kazakhstan 4
#10 Ecuador Ecuador 6
#11 Bolivia Bolivia 6
#12 Hanguk Hanguk 6
#13 Costa Rica Costa Rica 6
#14 Puerto Rico Puerto Rico 7
#15 Guatemala Guatemala 8
#16 Saudi Arabia Saudi Arabia 8
#17 Barbados Barbados 8
#18 South Africa South Africa 8
#19 Prathet Thai Prathet Thai 9
#20 Bahamas Bahamas 9
#21 Việt Nam Việt Nam 9
#22 Malta Malta 9
#23 U.A.E. U.A.E. 9
#24 Cymru Cymru 10
#25 Macau Macau 10
#26 Panama Panama 10
#27 Moldova Moldova 10
I have 1757 players for sale and I'm $25,835,360 in debt. Buy them at outrageous prices, or be selfish and make me go bankrupt. You decide, BB.