Found out I already had a bonus. I have 2 extra batteries for my D50. The D50 takes the EN-EL3a battery, but can also use the EN-EL3e. The 2 extra batteries I already have are the EN-EL3e. The D300 takes.... EN-EL3e. SWEEET.
Also the EN-EL3e batteries (both Nikon and my backups) are grey. The EN-EL3a is black. So I wont have any issues with putting the wrong battery in the D300.
For the EN-EL4 battery (to get the 8 fps) it is $95. The charger is $120 and then you have to also get the BL-3 battery chamber cover for $50.
I think I'll stick with my 3 EN-EL3e batteries and the 8 AA's (I have a bunch of Ni-MH rechargeables).