get a 2nd hand SB600....then learn abt flash. You will be amazed how mush there is to learn abt flash than just simply popping it up and firing. then get some acc to compliment your flash ....when you find yourself restricted by the SB600, then sell it to get the SB800 ( or u can keep it, by that time you might learn abt Nikon's famous CLS ).
After that you might find having 2 flashes not enough for you ... lol
A conservative advice from me.... use the lower end one first, after which u feel restricted by it, you will recognise the value of the higher end models.
I find that lotsa photographers getting the higher end cameras and acc but yet using only the features and abilities that a entry level products can do. :think: