Sorry, I can't quite follow what you are saying, but:
- why not use PGP web of trust ? Or are you doing that ?
- I should be able through your web of trust, to sell $ or BTC, to whoever wants to buy it in the web-of-trust graph, but your system should break the deal up into several buy/sells between two adjacent vertices in the graph (people). Some transaction can even be done in person.
Its techinically PGP web of trust just think Bitcoin web of trust... the owner of the address can only sign for stuff. Maybe check out the system and
then tell me what needs improvement hehe