I think we must forget about price back to 1200 it's time for wake up from your dream. Bitcoin is never again reach to $1200
additional note: when you see one price on exchange A at $300 and on exchange B at $270 ... of course you would want to buy the bitcoins at EXCHANGE B for $270 and sell it higher at EXCHANGE A for $300 so that's how prices are influenced at different exchanges ...
I never see range price too deep like that, the best range is $5-$7 at different exchanges
Really?? ..
recently Chinese bitcoin exchanges were like 30--60$ usd higher than the USD exchanges ... pretty crazy case of arbitrage there =] (cny exchanges were $350 usd and ... usd exchanges were $290-$300 per bitcoin)