No, there are no offers for subscribing to InsideFlyer I am aware of - and definitely no offers that would make it worthwhile to pay for 100 subscriptions.
Most lucrative offers nowadays indeed are the credit card sign-up bonuses offered in the US.
Offers outside the US are more limited in scope and youŽll generally have a very hard time accumulating enough miles in a single program to get any "great award" thorough non-flying activities alone.