How to?
By their example. Tell them what you bought, why? What is the advantage of buying from TripleClicks. If you do not want to buy and your members buy,,,, means that you will benefit from their purchases (percentage of every purchase you will receive your member).
Everybody knows that!
You will not encourage anyone to purchase them if you were not the case! Because the SFI great team. All buying but all and participate in the profits.