http://shop.penskeshocks.com/8900-SERIES-FZ09/ Someone was looking for a rear shock alternative. I think Penske makes a robust shock to order. Of course I don't know which one you want, but it's a decent brand to investigate for a moderate price tag comparatively speaking. The Jap bike riders seem to like them even if they are more than some shocks.
Another option if we can get at least 5 orders is Touratech will build a "Touratech Explore Shock" for the TR-650. They have two orders so far. Contact Arron Jennings at 1-800-491-2926 Ext. 230 for more info and to get on the list. The price he quoted is $795. Jack Splash commented on this over at AdvRider.com with more details about the shock. Here - http://advrider.com/index.php?threads/husky-tr650-new-owners-stupid-questions-thread.850525/page-339 Post # 6778
Wilburs, Ohlins, Mupo and Race tech all can do for Terra. They are all pretty expensive and any would be pretty bloody good. Im still saving for my upgrade.