You guys should give everyone one free week upon signup, long enough for anyone to try the game and get the gist, but not long enough to get a huge amount done. You'd need to buy the month (or more) to finish your game. Personally, I don't mind a $2 risk on a game I knew little about, but most people are fairly paranoid about spending money on apps.
So that's just my suggestion, I thought about this because my family is interested in the game but they don't want the spend money without trying it first.
Also make an iPad version!