Just sold the boat you describe a couple months ago. Mine had the HO 285HP and the 1:1 transmission. Mine was very clean with 650 hours on it. Depending on condition I would say very rough numbers would be $8000 to $12,000 range depending on condition. I would say the lower end is more likely given we're at the end of the season and it needs brake work on the trailer. More towards the higher end if it's clean, trailer was good and you were looking at it in the Spring.
2008 Prostar 197