You don't have to buy anything, just use some "like exchanges" - use google to find them, but if you really need help - from some time i used addmefast.com , LINKCOLLIDER , Like4Like
To be honest it doesn't wor for long term..
Do you think addmefast.com still working i think those you mention site it will not work. free is not working anymore.
i know there is other site that offering a small amount for youtube views. it works good..