The cheapest registrars are not always also the best registrars. There are many things to consider.

How good is  support and service ?

Are there promos and specials available ?

Are there any hidden costs ?

How is the interface ?

To  protect your whois data is often offered for free and thats great but there are also a lot of registrars where you need to pay for this feature.

 

 

E.g. at name.com you don´t pay  anything for this feature but at GoDaddy. the costs are $8.99 per domain/year (if you don´t have 5 domains there) and  at Moniker.com currently  $4,00 per name/year for whois privacy.

Of course there is a way to transfer domains out to an other registrar but  if  you  think before you register a domain name somewhere it´s often not reguired and you can save your money.