I have a serious quandry on my hands, and I would really appreciate some unbiased input. I'm slowly working on building up gadget bag with quality gear, and on return from my current deployment, had finally decided which new 'daily' lens to buy: The Nikkor 24-70 f2.8. I now have a chance to get a Nikkor 400mm f2.8 - the holy grail of long Nikon primes for $3700. It's about eight years old, so no VR, but that's not a big deal to me. It's got a few scuffs on the finish, but is reportedly mechanically and optically perfect (it would be inspected closely before purchse). So, the question is, do I buy it or not? Because of house renos that are ongoing I can't really afford to buy the 400 and the 24-70, and while I would use the 24-70 every day, the 400 would not get used all that often. HOWEVER, when you need a 400mm, nothing else will do. This is the first used one in my area in about three years. So, do I buy it because it's there and limp along with my poor old 18-70 f3.5/4.5 kit lens for another 6-12 months, or do I let it go and get the glass that I will use every day, and figure that another of these will come along eventually? HELP!!!!!!!!!