Stupid question?

[simba82]

I'm following the Bitcoin developments for some time now, and am about to jump in (waiting for my exchange accounts to get verified).

So, this is probably just a stupid question, but I can't get my head around it.

The buy/sell differences between the various exchanges can be very big. What would stop me from buying at, for example (and not considering the now offline mtgox) 1btc at $651 at bitstamp (which as per today is at $651/$642 buy/sell) and then selling that same bitcoin at another exchange that offers a better selling price, say Kraken (which i believe now is at $673/$670).

Presto, that's $30 per btc in the pocket for barely any effort (and i think i've seen bigger differences between exchanges)... But surely, it won't work that way?.

Damn, i feel like a noob
Can anyone enlighten me?? 

[HerrAndreas]

what you have in mind is called "arbitrage".
yes it does work, but keep in mind that you are not the only one to try and make a profit of it.
the more people try to do that, the faster the prices will even out (you can even tell where most people are buying and selling just from the price difference - as it very quickly becomes equal to buy price + transaction fees).
when you take the transaction fees of the different exchanges into account the profit you aimed for can very quickly turn into good old speculation on a rising price if the prices change faster than your btc transfer arrives.
 
having said that:
yes it does work, but there is a big BUT.

[Acidyo]

what you have in mind is called "arbitrage".
yes it does work, but keep in mind that you are not the only one to try and make a profit of it.
the more people try to do that, the faster the prices will even out (you can even tell where most people are buying and selling just from the price difference - as it very quickly becomes equal to buy price + transaction fees).
when you take the transaction fees of the different exchanges into account the profit you aimed for can very quickly turn into good old speculation on a rising price if the prices change faster than your btc transfer arrives.
 
having said that:
yes it does work, but there is a big BUT.

also don't forget; add exchange fee's to the rest of the fee's too, usually it's 0.2%.