Stackoverflow is both asynchronous and asymmetrical. The former lets the dev answer when convenient. The latter means the dev knows that their time is being multiplied and potentially lending help to large numbers of other devs over a large period of time. That is a compelling idea. A phone call is one-to-one and inconvenient. $45/hour is also hugely underpaid in the US at least. So, the proposed system is underpaid in both $$ and personal satisfaction.
I wonder if OP's product would work better if it was more like StackExchange bounties. Post a question alongside a non-refundable dollar amount. When someone posts an answer that solves your problem, you can award them the bounty. If no answers are accepted after a reasonable amount of time, the bounty is forfeited.
This setup contains risks for both the asker and the developer, but I think they're balanced pretty well, and the incentives are set up correctly.
