If your budget is $300/hr, then I would either contact the core developer(s) or use one of the consulting companies specializing in that software. Also there is

If your budget is $300/hr, then I would either contact the core developer(s) or use one of the consulting companies specializing in that software. Also there is a lot of cross-over in those groups, which you can use to filter the latter category. For instance for Postgres, scan the hackers mailing list for the most common names. In a lot of signature lines you'll see "EnterpriseDB" or "2nd Quadrant". You could also look at who is giving talks at the conventions. As a freelancer (IMO an exceptional one), I would love to charge $300/hr, and I feel for the "drop in and recommend/make a fix" engagements I would be worth it. But realistically at that price people are paying for lower risk. They want high confidence that whomever they hire will truly solve the problem. Usually that means hiring a company instead of a person. It's true there are as many bad consulting shops as there are bad freelancers, but it's still a little easier to pick out the top ones by their public activity, and you know they are open for business if you want to hire them. I would avoid "marketplaces" like gun.io etc. As much as they try to maintain high standards, they still wind up competing on price. My own rate is nowhere near $300/hr, but it is still too high for those places, so I doubt experts with real name recognition are active there.