I own a Nikon D90.
I own 3 lenses;
1)35mm f1.8 G very good for low light, still needs a tripod when light is very low.
2)105mm f2.8 G VR2 Micro this is a very good lens for snakes (but costly)
3)18-200mm VR2 zoom a good lens in brighter lighting

the 35mm is about $200
the 105mm is about $1000
the 18-200 is about $800

A D90 is an excellant camera in it's price range....(around $3000 )

A full framed camera is simply out of my budget, but I would if I could.....
D700 is 4 times more costly because lenses are $2000 to $8000 each.......!

Harry

P.S. You will use a tripod a lot ( more than hand held shots).