Coinbase.com will allow you to buy up to $100 with a 1% fee. It's pretty much what I'm recommending these days to Americans.
So if you buy $5 worth of bitcoins, it costs you 61.2% in fees.
If you buy $50 worth of bitcoins, it costs you 9% in fees.
If you buy $100 worth of bitcoins, it costs you 6% in fees.