Amazon developer backlink- Is it any good?

Guys,
I've been sent an email where someone reckons they can get me an Amazon link DA96 for $67
They show an example and their link seems to show in the "developer info" on the Amazon product page.
So, is this worth it or is there a cheaper way by doing it yourself?

There was a guide here on BHW but I can't find it.

You can do it for free.