My input would be that I have a generic "go-fast" FULL boat cover that spans the entire boat and covers about 1 foot down on both sides of the rub rail. It is not some custom job and hence didn't command that kind of price.
This has lasted 5 winters for me and several more for the guy before me and shows NO signs of wear. You might want to just do a taste test on going that route. You might find you have a cleaner boat come summer, and less work each winter.