I have really gotten into photography over teh last two years and i have been paid for several dozen jobs. I think it is time for an upgrade! here are some options and some questions: Sigma 17-70mm f/2.8 Sigma 70-200mm F/2.8 Used Nikon D200 I was going to buy the D200 because a client hired another photographer because his camera was "more professional" even though her photos where dreadfully over-exposed. Would buy a vertical grip and an extra battery with the camera. Would love to buy a D300 or D3, but don't have that much money right now. I can get a used D200 from B&H for as little as $1099, any huge problem with a used camera from B&H? or I know it makes more sense to upgrade lenses, but nikon glass is so much $$$, Sigma makes great glass at about half the price and i dont mind buying third party lenses. the main question is, when i do one day buy a full frame camera(a nikon) will these lenses still work with it? I apologize i still dont understand the whole: will DX lenses work with FX sensors thing. and i am sorry i am like the millionth person to ask.