Good advice from BYP. If you do not have the skills, but want your drive shafts repaired, find a local driveshaft repair specialist. Yelp my be helpful in conjunction with Yellow Pages.
I've heard nothing but bad about aftermarket axles for Boxsters, at least from track guys. Unless the OEM axles are clicking/grinding, cleaning and new grease and boots is probably a better bet for folks needing a replacement.
I'm not debating that OEM or rebooting OEM axles is the way to go.
The site in question has lots of good OEM parts. I was surprised to see the axles listed on their site. Given their other products I just wondered if anyone had given these things a try.
I have had some bad experience with those generic auto parts store axles on a Golf. They are subpar even for just a commuter car. I have a friend who owns a repair shop and anytime an axle is not beyond repair he sends it out to have it repaired as the auto parts store axles will only last 6 months to maybe a year or two even on your average minivan. There are axle shops who rebuild them. Depending on how bad it is they just put oversized balls in the joint.