Crawl Space Encapsulation and Moisture Barrier Installation

I have an older house with a vented crawl space under the main floor, and it has become a real problem. Every time I go down there to check the plumbing I notice a musty, damp smell, and lately I have seen small patches of mold growing on the wooden joists near the foundation wall. The dirt floor stays wet most of the year, and a hygrometer I left down there for a week read close to 80 percent humidity even on dry days. I am worried this moisture is slowly rotting the floor joists and subfloor, and honestly the musty smell has started drifting up into the living room through the floor vents, which is not something I want my family breathing.

What I am looking for is a contractor who can properly encapsulate the crawl space: seal the vents, lay a heavy-duty vapor/moisture barrier (at least 10-12 mil reinforced polyethylene) across the entire dirt floor and up the foundation walls, tape and seal all seams, and insulate the rim joists. I would also like a recommendation on whether a dehumidifier or a mechanical ventilation fan is needed to keep humidity under control long term, and whether any existing wood damage should be treated before the barrier goes down. The crawl space is roughly 900 square feet with about 24 inches of clearance in most areas, so it is workable but not spacious.

My budget is modest since I already spent money on a roof repair this year, so I would appreciate a contractor who can work efficiently and give me an honest assessment rather than upselling extras I do not need. I want before-and-after photos, a written scope of what materials will be used, and some proof of past encapsulation jobs. Please include your estimated timeline and whether you handle the mold remediation yourself or if I need a separate specialist for that part. I would like to get this scheduled within the next few weeks before the wetter season starts.