sketching out HTTP 402 workflow

I'd like to sketch out a design and workflow for HTTP 402 that I think
would be possible to implement as a proof of concept

im trying to design a payment system using SoLiD and HTTP 402 ... I wonder
how it would go?

1    Alice wishes to view resource X costing 1 bit from wallet W
2    resource X is ACL protected
3    Alice visits controller website and indicates wish to view protected
resource
3    Controller website sends back HTTP 402 saying payment required and
gives a protected location Y for Alice to send a payment
4    Controller website subscribes to location Y
5    If Alice is verified as sending a payment she is added to ACL of X
6    Payment is subtracted from wallet W
7    Alice can view resource X

I'll be using the SoLiD framework for this.

Anyone see any obvious flaws in the workflow?

[1] https://linkeddata.github.io/SoLiD/