That sucks about the tube – Who sells a rod, especially a high end rod like an XP without the tube? What did the guy do, prop it up in the corner when not using it?
Anyways, Madison River Fishing Co. (http://www.mrfc.com) sells stock Sage Aluminum Tubes. More than likely as with your situation with Sage, the tube will probably not be the one that matches the XP. However, they sell them for $40 for a 2 pc rod and $50 for a 4 pc rod. The ones shown are tan with brown lettering. It might save you a few bucks at least. Cabelas also has some decent aluminum rod tubes for about $30…..
Jake