Several things come to mind, some of which may seem obvious.
ALL fluids should be changed BEFORE starting/running the bike, I emphasize all because I would include a complete brake fluid change and thorough brake line inspection for and signs of swelling/cracking or other damage. I emphasize before because the fluids will absorb any moisture present in the air of the storage area - even a climate controlled one.
The following is just something I would like to do before hitting the starter button and can be done before you purchase the bike as long as the current owner has no problem with the request.
If you can bring along a bike jack and if the owner will allow it jack up the bike so the rear tire is off the ground, pull the spark plugs, put the tranny in fourth gear or higher and SLOWLY spin the tire by hand to make sure the engine rolls over smoothly - I actually would do it sitting down on the ground next to the bike and using my foot to "push" the tire in it's normal rotational direction while someone helps stabilize the bike. Either the current owner or a buddy you brought along can assist.
The age of the tires (which I personally would replace if I purchased the bike) - frozen/stuck brake calipers, cracked leather goods, pitted chrome, dry/cracked drive belt. all the control cables will need to be lubricated and checked.
Take off the fuel tank cap and take a look inside, a little sniff may tell you if the fuel has been in there for the past nine years - I would count on having to drain/clean the tank and change fuel lines at a minimum.
A thorough looking over of the bike before purchase and then a complete going through after purchase will serve you well in the long run.