We are about to give up on Groups. It is like a stray dog for google. The filtering is hit of miss with groups. Our internal help desk gets 1-2 google group issues / week from our user-base of 70 employees.
Feel free to reach out to me via email (jaisen@). I imagine you're hitting the same pain points that many of the customers I've talked to over the last few months are. Hopefully what we're working on will address them and it's not too late.
Stray dog is an accurate description. Groups has not received the updates needed for use in enterprises but it's a current focus area for us (for reasons you mentioned).
We use whatever payment processor you us. So, for example, you'd connect your Stripe account and we process all credit cards using that account. Our pricing is at www.paidapi.com/pricing and based of the revenue tracked/invoiced.
