I generally advise the following when the floor seems pretty good but has worn carpet, tired upholstery, & is 20+ yrs old:
A) Use the boat as is while putting away $$ for a complete overhaul
B) Use the boat as is until you get too embarrased to run her & then sell at a discounted price to a DIYer
Additional thoughts: A new ski boat costs 40K+ A good used 10yr old ski boat costs 20K+ A worn out tired 20-30yr old ski boat is worth 2-4K+/-
To justify the cost of rebuilding as a DIY project & maybe some professional help is pretty easy to make the numbers work, in this manner you could spend 3-5K and come out with a really nice boat that will last for decades
To a pay a professional to do all the work becomes very hard to justify unless there is additional sentimental value to the owner.
Here are some rough estimates for professional work: Closed bow ski boat
Remove deck, motor box, engine (500-700)
Remove carpet, cut out flooring, remove foam (700-900)
Replace stringers IF NEEDED (rare on A/S boats) (900-1500)
Replace flooring w/composites, replace carpet (800-1000)
Engine/trans work (depends on hrs, cond.)
Replace wiring harness (same dash) (200-400)
Replace fuel hoses (all) (100-200)
Replace upholstery (1000-3000)
Return deck to hull, motorbox, engine, new rubrail, (600-900)
Above does not include any exterior finishing or trailer work.
PS I am always looking for the "B" boats above