A used Hobie Tiger might be a good boat for your purposes. I can't speak to "better built" but I've not heard of any problems with them and there should be plenty of used ones around in your $8,000 budget. And why pay for a racing boat if you are not going to race it?

All the new F18's are built to a class minimum weight so their hull layups are going to be about the same, and they are all great boats, but way out the top of your budget.