For open source software such as HAProxy contacting the contributor(s) might be the best approach (even if they don't usually do consulting, an hourly fee of $3

For open source software such as HAProxy contacting the contributor(s) might be the best approach (even if they don't usually do consulting, an hourly fee of $300+ should be convincing enough). Other than that Stack Overflow or a plain Google search might be your best bet. Moreover, there are services such as Gun.io that only list high-quality freelancers.