If 40 people had to actually pay $25 it would make no sense at all, but if people have an extra AMEX card and want to use their $25 SBS credit towards paying the Tapatalk license to make a DDF app be free for future users then there's some logic.
This gets into a discussion of is this $25 something extra that should be used on something you wouldn't ordinarily buy, or should you view it as cash and try to use it on purchases you would anyway be making.
The former is 'special' because you can 'pamper' yourself and splurge but the latter saves you $$ and is therefore like receiving cash(Ie pay your shul membership dues)!!
I recently won a $15 itunes gift card. They offered me either the card, or $15 cash. I took the cash because then I have a choice of where/how I want to spend it. Then again, it would have been nice to have a $15 credit on my itunes account and the $15 in my wallet doesn't really change my financial position!
With this however, a guy who has 8 amex cards could take home $200 if he spends it wisely as opposed to getting something he would never have bought and doesn't necessarily need.
Not to take away from the cause though!
If 40 guys donate I'll be the 41st to get it free!