It appears that if "friend" wants to sell this bike and is not planning on giving it away, he should be the one doing the rehabbing to get it in running condition. If you buy a new battery, there is no guarantee that it will run. I would never buy an inoperable bike unless for a basket-case price.
It is a good price based on current market prices.
08 Goldwing 1800
12 Ural Patrol