The SB-26, 28, 80DX, 600 and 800 will all work well enough. I think the SB-700 and SB-900/910 are no longer TTL compatible. Of the lot, the 80DX might be the most affordable because it is neither here nor there in terms of system position. It isn't iTTL, and was made for the D1/D1x while maintaining TTL backward compatibility. You may also have a serious look at some of the Metz flashes with appropriate adapters. I have 40MZ3i and 54MZ4i flashes, both of which have Nikon TTL modules. The SB-24 is a small flash that is useful for fitting into a small pocket of your camera bag, but the GN is nothing to write home about.