Based on all the feedback I have seen at this forum over the past 2 years, I decided never to make a purchase for the generation of points with MyPoints. I have earned over 30,000 points in the MyPoints program with the only cost to me being the time it took to point and click and fill out info, etc.
I also learned to only redeem points for electronic tranfer awards such as Hilton HHonor points as there is nothing to be mailed and the reward appears in a day or two.