Just buy what you can afford now. No need to go for the highest speed. The price of such IT stuff will keep dropping. Its a matter of when you actually need it - not just "want to" have it. The sales rep at SLS, IT show or any other shops will try to sell their latest and "fastest" CF card but I told them I'm not in a hurry to get any CF cards now
Unless ... you need it for your rice bowl :think: