You want to buy this 1985 KTM two stroke dirt bike and it hasn't been run for 8 years its a 125 it has upside down forks and its missing a side panel. How much should you offer?

Are you sure it is a 85 with upside down forks? I didn't think they put them on production bikes until around 87. Anyway, I wouldn't offer more than $300. Unless you are going to race the vintage class, you're buying 24 year old technology that you don't know how much money it will take to get running.