Mike, here's the thing:
My Mother deferred her personal happiness all her life, always for the benefit of those around her - coworkers, family, kids, grandkids, whoever. She never gave herself much of anything, always feeling like she would do it "later." She always said, "Someday I'm going to..." And that "someday" was a blurred date down the road in her future. As she got older, it seemed like "someday" was finally going to be when she retired from working. She worked and worked, and finally, after all those years, she retired. 35 days later she died of undiagnosed liver cancer.
Think about that.
What is your motivation to own a Boxster? Is it an age thing, a status thing, or just something that will be fun to drive? If you're having an age crisis, talk to your shrink. If it's a status thing, question why you need to prove yourself better than your neighbors. If it's a fun thing that will put a smile on your work-weary face, then why not? Don't you deserve something in your life that makes you happy?
If you feel you need to hide it, you're buying it for the wrong reason. A beautiful car like a Boxster needs to be shared with your loved ones. Maybe your wife or kids have similar thoughts of enjoying a drive on a great day with the top down, but think it's beyond the scope of their lives.
Nobody says you have to buy a brand new Boxster - there are plenty of great used ones for sale. The one I own was built in 2002, but it looks and runs like new. It's awesome. Cars like mine are around, and can be purchased for less than $15K without a lot of effort. I own three cars, but the Boxster is my hobby car, sheerly for the pleasure of owning, maintaining, and driving it. You could start with an inexpensive used Boxster, get to know the pleasure (and $$$ pain) of owning one, and then buy a new one later on, once you've decided owning one is what you really want to do. Who knows - after you have it and the novelty wears off, you may decide it isn't for you after all. If your buy-in was at lower cost, you won't be (as much) money behind if you decide to sell it.
At the end of the day, if you buy this car and feel you have to hide it from your family, you need to get a vanity plate that reads "Mistress." Because it's exactly the same kind of thing.
I say go for it, but do it in broad daylight. A boss I had years ago had a sign over his desk that read, "If they're running you out of town, get in front of the crowd and make it look like a parade."
Dave