I'm not sure if the $3.99 site is legit as I've never seen one that cheap. I personally use Optinom but 1and1 is cheap too. Optinom is $8.20 and 1and1 is $6 if I'm not wrong. If you buy from 1and1 - USE THE US SITE! They charge $6 on that, but charge £9 on the UK site!
godaddy.com is the best I would suggest their prices are also reasonable for the service they provide!! I mean WOW Merged Post: & on godaddy.com The sale is for .info for 1.99$