You've gotten some good advice here. I would just add keeping a close watch on Craigslist in your area. I've had very good experiences and found some amazing bargains. And keep on the lookout for estate sales in your area as well, there's a good chance the sellers may not know full values. You can always save money by going with a third-party lens. I have a Tamron 300/f2.8 and a 2x tele-converter that I found on Craigslist and works great. My experience with eBay is mixed. I bought my Nikon 70-200/f2.8 and it went very well. When I bought a used D3, the seller lied about the shutter count.