Bitfinex often has a leading price, or sometimes is LakeBTC step ahead, no matter, the key is that price gap usually is $10 between them and BTC-e.
This tells you what the real costs of Bitcoin transactions are. Looks like they're about $10 per round trip, in and out of Bitcoin, or, at current prices, about 3%. This is an inefficient market by modern financial standards.
It depends on the quantity of bitcoin you transfer in and out of fiat. Wire transfers usually charge the same for any transfer, no matter how big or small. However, they can take a week to complete which is really inefficient and ruins arbitrage opportunities.