Review our app's subscription plans/page
noodle: i would suggest calibrating the transaction fee % to make it end up being a moderately more expensive option if someone were to use it heavily (dunno if 9% is optimum for that or not), and then make the free one more prominent.  that way, its a solid income generator if people don't want to pay upfront. this way, not like its losing you any money or an inconsistent revenue stream like it would be if it were ad-based.  (also, i don't like the basecamp model where the free version is unobvious).i think you would be the best judge on the needing another tier.  i think, though, that if you take the previous suggestion i made, you're probably fine.  make the free tier enough more expensive that its useful to use on a trial basis or on a non-professional basis, but if you want to start making some serious transactions, you'll want to have a paid sub./$0.02