As much or as little as you are willing to pay, and the lawyer is willing to accept. I am not being flippant. A large, complex trust estate with heavy duty tax consequences and major investiment strategies will require a great deal of highly technical work. A simple trust estate (which probably shouldn't BE in a trust in the first place) can be prepared by the client himself using books from Ten Speed Press and forms available at the local stationery store.
Our Bay Area lawyer, whose practice is limited to trusts and wills, charges around $1,000. I've known him 30 years and recommend highly, if you want to email for contact info ([email protected])