I operate a TBUS port on Lake Michigan. Unlimited Members ($73 Freshwater) get towed for free. I get paid from Boat US so long tows are welcomed. My Non Member rate is $225 from time I leave my home port til I return. Credit Card #before we leave. Most tows are at $450 and up. I have a 25 mile 1 hour response area and need approval from Boat US to bill outside of my area. Always granted so far. There is a $2500 limit. Which will get you to a port from almost anywhere in the lake.
Salvage is billed to an insurance company. Check your policy, some cheapo ones have a $5000 salvage cap. Rest is up to you. Salvage can be very expensive. Make sure your environmental coverage is adequate. The USCG can order an clean up company if you have a spill and bill you thousands. One owner was hit with a $19K bill. The last thing on insurance is to make sure you have an agreed value not market value policy. Cheaper is not better.
Towing is half what it used to be 10 years ago in the Midwest Most marinas are half full. Tell all your friends to buy a boat