In short: A fundable evaluation section names the questions, the design, a defensible budget, and the evaluator, and it's written while the proposal is still being built.
The evaluation section can sink or carry a proposal. These pages cover what reviewers look for, logic models, evaluation plans and budgets, and how an evaluator helps at the proposal stage.
Vetting an evaluator comes down to specific questions about fit, method, and availability. Credentials alone won't tell you who's right for the work.
Evaluation pricing tracks scope, and quotes vary because firms are pricing different amounts of work, which makes scope the conversation worth having first.