I was thinking $5 buy in would be a small enough buy-in to encourage a few people to play, not many people want to put $10/20 into a single game if they are not fairly confident of thier ability.
$5 still gives the winner $22 I think

, but if more people want to play for $10/15/20 buy in then its cool
For the lads that don't play, try pokerstars play money NL hold=em tables to get a feel for how the game and betting system works, but don't pay too much attention to the scale of bets/ how many people play thier hands, as play money tends to end up a bit free-for -all as it dosn't matter if you loose. To get a good feel of how "real money" poker works then play the $0.02/$0.01 cent blind limit hold em games, keeps the betting sensible and means you won't loose a bucket load of cash learning, but people still bet sensibly as its real money