I will be in Manhattan from mid-week (staying at the M.O.) and want to buy a US PAYG / Pre-Pay SIM card. There seem to be different providers and (from what I can) see they even have different types of SIM card. What should I get for my standard UK tri-band (unlocked phone) and where should I get it ? Is there a complicated ID process required or can I just walk in somewhere and buy one ? Ebay will probably be too slow for my needs