Hi, hi... I noticed that for domain reselling, it usually costs like $9++ or more or less to register each domain. Yet, how do sites manage to break even by selling their domains as low as US$5(apart from reselling for "not so reputable" domain registrars)?

They don't.

They either offer other services (especially hosting), have hidden
charges, or give only email or chat support. Those that do offer
phone support are able to depending on their leverage.

attracting customers to sell them other services like hosting, servers, webdesign etc..

marketing strategy :)

also this *strategy* is much cheaper than PPC ranking and afterwards word of mouth does well.

Ahh, thanks for the insight. ;)

You can check around. There are some top domain registers that have resell accounts for under $7 per name and they have promos through out the year where resellers can get names for under $5.