I don't know, if my player wanted it I'd agree with a 10k price. His str may be higher, but his claw attacks have a poorer critical range and multipliers, plus he dosen't do as much damage as with a greataxe. He'd also lose all his AC bonus and I think bears are large so he'd lose that too right? He can't affect things with damage reduction, and when he isn't raging he's wearing hide armor.
Lets compare it to Rhino Hide armor from the DMG. Rhino hide is +2 hide armor, it doubles damage done on a charge, and the cost is only 5, 165gp. I don't know what str your barbarian has now, but I doubt this item will increase it much. Also with Rhino Hide there isn't any drawbacks other then what you normally get when charging. With the Bear Hide armor you probably lose a significant amount of AC since the MM Brown bear has AC15 and you'd probably lose another 2 for raging. I'd accept the 10k as a DM, but I'd probably also accept it as equal to the Rhino Hide. It may be cool to be a bear, but it's also cool to wield a +1 Keen Greataxe... It equals out...
Lets compare it to Rhino Hide armor from the DMG. Rhino hide is +2 hide armor, it doubles damage done on a charge, and the cost is only 5, 165gp. I don't know what str your barbarian has now, but I doubt this item will increase it much. Also with Rhino Hide there isn't any drawbacks other then what you normally get when charging. With the Bear Hide armor you probably lose a significant amount of AC since the MM Brown bear has AC15 and you'd probably lose another 2 for raging. I'd accept the 10k as a DM, but I'd probably also accept it as equal to the Rhino Hide. It may be cool to be a bear, but it's also cool to wield a +1 Keen Greataxe... It equals out...