Is $20,000 to perform full crawlspace encapsulation and french drain installation a fair price?

I have had three separate crawlspace guys come out because I noticed my hygrometer reading 90%+ humidity. I just bought the house six months ago. However, as there isn't any mold at all, I'm wondering if it's reasonable to just do nothing. They've told me they suspected maybe the previous homeowner had some remediation done, but I'm questioning if it's reasonable to just keep watch and if mold starts to grow, then do something. I do have a vapor barrier, and it is all closed. I've also learned that open vents don't decrease humidity.