Payment Protected Resources -- Using HTTP 402

Many of us are now using web ACLs on a regular basis.

A rule may look like:

<>
    <http://www.w3.org/ns/auth/acl#accessTo> <.>, <> ;
    <http://www.w3.org/ns/auth/acl#agent> <http://melvincarvalho.com/#me> ;
    <http://www.w3.org/ns/auth/acl#mode> <http://www.w3.org/ns/auth/acl#Read>,
<http://www.w3.org/ns/auth/acl#Write> .

This essentially says that my user ID can have read and write access to the
named resource.

I thought it might be an interesting idea to extend this type of access
control to allow payment protected resources.

So each server will maintain a balance for each user, as is typical with
many commercial business models these days.

If the user does not have any credit the server will return a 402 HTTP
response code, explaining the cost of the item and how they can top up
their balance.  This could either be via a traditional payment method such
as Euros, or, say, via a balance in crypto currencies, or as part of a
loyalty / reward scheme that the web site issues.

I'm wondering if we can extend the vocab we have to add payments?

Perhaps a simple way would be to subclass #accessTo with #paidAccessTo

Then have in the ACL rule a simple payment amount (or rule)

Then say something like:

<#amount>  0.001^^BTC

Anyone have any thoughts on whether this could be implemented?