Hi Rob,
While I like the idea of instant commissions one thing I do worry about with slightly more expensive products is having to deal with refunds.
I'm sure most experienced marketers are used to dealing with refunds and have no qualms about giving them but I wonder if newbies who make sales will be as prepared to "give up" their $67 or $97 payment when the customer asks for it. Like you said, many are on a tight budget so refunding a $97 sale could be a real sore point for them.
I just wonder if this would cause a problem if you state a money back guarantee, but then have affiliates who don't honor it?
At least with a delayed-payment affiliate program, the merchant handles all of the payments/refunds and then the check/paypal payment is made after all refunds have been taken care of.
I don't want to put a downer on your idea, as I like your script from what I've seen in the WF, but just wanted to give my opinion.
All the best,
Richard