[BoxsterLS376]

That could be an easy fixer too. the 446 code does not relate to the others so you have 2 problems, but unless the car has been driven a lot with those problems there may/may not be a big issue. If the car seems to run well but has those issues it could simply be that the cam sensor has gone bad, or that the little timing pad has broken off of the tensioner. So if you fix that issue, it may be a good car.
Really just need to remove the valve cover on that side and do a quick visual inspection, or you may be able to get a Durametric and compare values of the cam sensors etc.
Either way it is a gamble, I would definitely have a professional do a PPI on it before you lay out $3k for it un unknown condition, it will be the best $150 you spend on the car.