If it hasn't been used since 2006 it obviously needs to be serviced. The sticky might say something about that.
By the time you get done with that, the price approaches a new B2 sold at MAP. Some places will service a new reg for free for x years. So your new used reg may actually cost you more after only two years, if you follow atomics maintenance schedule. Of course, you will not be building as good a relationship with the lds.
There was a guy in our area who bought an atomic from an lds. When he wanted to have it serviced, he wouldn't to go back to the shop he bought it from. So, he goes to another shop to have it serviced and has a problem with them too. Finally, he sends it out of town with more problems. Comes in our shop and wants us to fix it for free because the last shop was an atomic dealer and the service should be under warranty. Really?
What's the point? Find an lds that you like and trust, patronize them and if you have problems, you will stand a lot better chance than buying used off the internet and it will be cheaper in the long run.
Back to the original subject on what to look for. You might want to have the sale contingent on a technician inspecting it during the servicing process. If it was used in salt water and left for 10 years who knows what shape it is in. If you have to replace hoses, etc the deal is not so good.