For a long time, I answered quote requests with a PDF and a detailed pricing grid: this much for front-end, this much for back-end, this much for mobile. It worked, but it placed the conversation on the wrong ground — price instead of value.
The format
Six pages. No more. One page of context, one page of problem, two pages of proposed solution, one page of milestones, one page of pricing. Signed at the bottom, dated.
The client reads it, understands what they're buying, and signs or asks for an adjustment. It's short, precise, and replaces three email rounds.