http://pe.usps.com/text/dmm300/ratesandfees.htm#wp1008795
http://payments.ebay.com/ws/eBayISAPI.dll?EmitSellerShippingCalculator
I believe first class is the same cost no matter where (in the U.S.) the destination is. I don't pre-pack my items either because I have lots of buyers with multiple wins. Like I said before, I always found calculated shipping to be a PITA, maybe look at some similar items to the ones you sell and see what kind of postage is being charged. Or just weigh it and add a small handling fee. It's unbelievably easy for me to just use first class, print the PP label, and put pkg in the mailbox. Piece o' cake
