ISO someone to oversee my design build

[Anonymous]

We are about to sign a contract with a design build firm for a new build, and we have been advised that we should find someone -either an architect or a construction manager - to periodically check in to make sure that the builder is doing what he promised, and to certify that work has been done to trigger draw payments. Would be grateful for a recommendation for someone who would do this service at a reasonable price.
Many thanks.