All of our products are sliding scale, and that is impossible to implement in Heartbeat as it stands.
I can't even implement tiered pricing, as it's impossible to create more than one product related to one group.
This means we will have to use a really clunky work around that will take us forever (manually entering each new group member as fee waived).
N.B. There is already a request in for this feature, titled "BuyMeACoffee", but it would not allow me to upvote it. So you can automatically add 41 upvotes to this suggestion!