apologies for a new "where to buy a foreign sim card" thread and i've probably phuglied the search process but what i've found didn't help...

goalie-parents are sfo-fra tomorrow (friday aug 17) and will arrive saturday morning aug 18. i want them to buy a german sim card (vs one of the compnies that will give you call back svc or a sim card prior to leaving suchs as telestal, etc) and i'm trying to find a specific location or two at frankfurt airport (or even in the sheraton as they overnight there before heading on) where they could take my unlocked nokia and buy the sim card. also does anyone know of what the going rate and or if there any specials going on (for lack of better terms) and which carrier is preferred-i saw both vodaphone & t-mobile mentioned in the searches but i couldn't get a feel for either one.

thanks and apoliges for the last minute request as goalie-parents forgot to check and i just found out from them a few minutes ago.