Exchanges for BTC/USD with lower minimum and fees

[maokoto]

Hello everybody. I have been trying several exchanges (coinbase, bitfinex, cryptsy) but they have a somewhat high minimum trading amount (for example it is 0.1 in Bitfinex). Do you know any exchanges with lower / no minimum?

And what about trading fees? is there some with lower fees than 0.02%?

Thank you very much in advance.