Stu are you already using a nikon dslr? only reason i ask if because if your not then you wont have spent out on any lenses
have a look at the sony DSLR,s they perform just as well if not better then Nikon, at a fraction of the cost
in fact sony make all the top range Nikon sensors and use the same in their own camera,s as Nikon do
sigma and tamron make lenses to fit sony
I am going to be totally honest here i will never ever buy another Nikon,
The D300 is my main camera the over all build quality is very poor, it has been back to Nikon 4 times in a year for simple repairs buttons falling off the whole camera cover coming away as the glue failed,
I fully believe now in the mass production market Nikons quality has gone down the ski slope fast, I wont convert to canon either as they are just as poor and after sales services is rubbish, they to fail to admit major issues with the top of the range cameras such as red dots in the pictures,
I will be looking either at a range finder , or a sony, and believe me my Nikon at 16 months old needs replacing its had it