Winterizing a boat

[FlukeU2]

Hi I have a question. Maybe someone can help. I have a 23' 2015 tidewater with a 250hp Yamaha. I have always let the dealer winterize the boat for me and also let the dealer get it ready for the spring time. I'm a mechanically inclined person and feel I can do everything myself to save money. Is it worth doing myself? Around how much would it cost to winterize and get it ready in the spring. And what is absolutely necessary to do and what things don't really need to be done? Like putting anti freeze in all the hoses for fresh and raw water. But are there things the dealer does that don't have to be done every year? Thanks