I got a 4 gig (2x2) of ram for my macbook through newegg for 76 dollars shipped. Not sure what kind it is (can't remember) but it had good reviews. I'd check there, lots of good deals.
It really depends with shipping. Right now it says they are shipped within 24 hours (refurb ones anyway) I ordered mine 2 weeks ago with regular shipping and got it in my hands 3 days later.... but that's not always the case, however I've never had a new apple product (refurb or otherwise) that said "shipped within 24 hours) take longer then 5 days to arrive to my door.
My friend got the 2 day express shipping for 18 bucks on her computer from Apple (shipping to Indiana) and she literally had it in her hands after placing the order Monday afternoon, on Wednesday afternoon, so if you are really worried, just pay the extra 18 bucks to make sure you have it.... but chances are you will get it pretty fast without it.