Is $15,000 to redeck with composite and reinstall current railing a fair price?

I bought my house a few years ago, and it has an old deck, likely from the late 80s. The deck has composite side material and mahogany top boards. The sides are in good shape, and the deck seems solid underneath, though a board on top and a couple on the stairs need replacement. I'm looking to redeck with composite, specifically Trex Transcend in a color I like, because I'm unhappy with how little time the stain lasts in the Northeast and how hard it is to clean. It gets very dirty due to surrounding trees, and power washing damages the stain. I was initially onboard with redecking but am surprised by the quotes, which are all over $15,000, leading me to consider sanding and restaining instead. I don't want to take on this project myself with winter approaching. I also want to evaluate the rest of the deck for damage if I redeck it. I'm not sure about the underside's condition but believe it was built well, though I expect some repair work. Contractors have informed me that Trex Transcend works fine with my existing 16-inch joist spacing.