What is a good website to order an unlocked iphone at a low price?

I want to get rid of my go phone but than I heard that you can put the sim card into an unlocked iphone. I want to do this, but I don't know what website I should order an unlocked iphone. If you have swapped your sim into your iphone, what website did you use to buy the iphone?|||ebay.com or buy it in in apple but with no activation then jailbreak with black rain just plug it into your computer open black rain and click make it rain and it will turn off for a while and then when its powered up again it will have blackrain app click on it download rock snow cydia. recommended do not trust john c unlock it with blackrain as i did