Hey Scott.... welcome back to the madness........
Three years ago I got what sounds like the same noise you're getting. I could hear it when I hit about 30 MPH. And, at the time my Boxster only had 21,000 miles on it. The bearings are not that expensive. At the time I paid under $60 each for the two rears from Sunset Porsche. The labor cost is a tab expensive. I looked at all the threads on DIY and convinced myself that my Indy should do this for me.
Here are 63 threads on the subject for your reading pleasure;
986 Forum - for Porsche Boxster Owners and Others - Search Results