That's a fairly average repair bill for one of these, so you got out okay. Sometimes they need a laundry list of maintenance and repairs if the previous owner didn't keep up with it. Control arms are a normal wear item so it's no surprise that they were due. Glad you got it taken care of.
Also a good idea to find a reputable Porsche specialist shop if you haven't yet. They know these cars like no one else, and the kind of care they need.