Almost every airhead I have ever purchased needed about $2K in work. That one looks real clean but keep in mind if it has been sitting it may, may need a lot of seals and rubber replaced. Forks, shaft seals, brake seals, push rod seals, etc. type of things. Also if the tires are old, no matter how good of tread they have, they probably need replaced. It could be one you get on and go around the world on who knows. It is worth what you are willing to pay for it and what you are going to do with it. As an investment it it seems to be priced high, as a Rider if it is in good shape it could be about right. I have every bit of that amount invested in my 84 R100RS LE but am just a bit anal retentive about my bikes.
If it turns your crank get it, ya know they don't make them any more.