Is it really arbitrage if you don't have a buyer yet? Aren't you really just talking about speculation, based on your prediction of where the price will go?
Maybe I'm off on my definitions, but I only use "arbitrage" when I can more-or-less immediately unload whatever I'm buying.
Once I discuss the 4 arbitrage items (I am using arbitrage as a "trade against" practice) I will review vehicles to easily trade the 4 amongst each other, such as bitgold.com and themoney-changer.com.