Duh, of all that time spent trying to knock some senses back into me, I can say, short of getting a Nikon D700 or a ultra-fast Nikkor lens, I am left with two options to put in some additional depth into my amateurish hobby - move into flash photography with a Nikon SB-900 or move into macro photography with a Nikkor 60mm AFS lens. Both cost about the same (Since I found a 6-month old 60mm AFS lens at $450 today)
Both the above options gives strong vertical depth in helping me understand more of photography and will easily extend the life of this interesting "sport".
I think I will just go for the flash, if there's no more complications...