[1.1.4] Unlocked. Best prepaid phone plan with EDGE?

I'm going the US (California) tonight and I need to get a sim card to use in an unlocked (1st gen) iPhone. (I will be needing 2 so if there are any special deals for that, please let me know).
I am not very demanding in terms of rollover or evening and weekend minutes, but what I'm looking for is a decent EDGE plan with no contract at a good price.
I am sure many of you have researched this already and can give me good advice.
Contracts are hell in the US!
Thanks guys, I know I can count on you.