Honestly the pricing is the real unnerving part here and it's definitely going to be a deal breaker for much of your audience.

Personally I'd prefer something like this: I enter my current flight details and the price I was going to pay (your experts should be able to verify this price as correct pretty quickly?), and then your experts would give me a better flight plan and I'd pay you 10% of the difference or something, and nothing if your experts don't find a better plan. This way I'd always feel like I'm 'winning' by using your service and not taking an expensive shot in the dark.