Thanks for the insight, Derek.
We have only a few surveys here and I don't find a way to qualify on a regular basis. Videos pay low, IMHO the whole "free credits" section takes too much of my time.
Therefore I buy my credits, about 15 $ in total in the first three months, only major investment (50 $) being the clubs that I have now, G20s, when becoming Master. From then on I payed 10-15 bucks per month, using the very beneficial Zong deal, about 3,000 cr for 15 €.
I used the Tour-SD long time, then changed to the lvl 33 Callies (playing less now).
It's not free but a budget pastime compared to many others, e.g. real golf or nights in town or a wife ;)