Scarab is a nice boat that will hold it's value pretty well. The Fountain is a decent rough water boat but fairly heavy. The Wellcraft cat is the mutt of the litter- avoid it at all costs. The Regal Velocity isn't a Velocity, it's a Regal that looks like a Velocity and built under licence.
On the Scarab, Blown 588's are alot of motor. They're also expensive to maintain and repair. You don't mention what drives- on these boats you'll likely have TRS drives which have been discontinued for some time and possibly early Bravos that aren't going to hold up under bigger power.
With all used boats, the key is condition. Not just what it looks like on the outside but things like transom/stringer rot, mechanical issues, hidden damage/repair, etc. Not on emember on this board will disagree that you need to have whatever prospective purchase you're considering fully surveyed by a known high-performance marine surveyor. Not a generalist.
I don't know where Summerville South Carolina is but we do have some members down that way that I'm sure can help or point you towards boats. If you run across a fat guy by the name of "Fred"... run.
This might be helpful- where do you plan on boating, who goes with you and what's your budget?