Paid links work. Fact.
Paid links are frowned upon. Fact.
If paid links are detected, they will be devalued. Pseudo-fact.
If your entire link profile consists of dodgy links, and you are identified as a link purchaser, you are likely to find your whole profile devalued, and if you are particularly unlucky or have otherwise broke guidelines, you may fing yourself with a penalty, or a more insidious "loss of trust"
So, its up to you.
If all the links on the pages are sold, then I suggest it is only a matter time before they all get devalued and you're out of pocket. And as I say, if I were Google and had identified one instance of link purchasing, I would take a hard look at all your other links, and possibly other practices your site engages in.