wat about just to trade him with lens?
is the 18-200 6.3 @ the long end? No, it is f/5.6 at 200 mm.
The 50 mm f/1.4 is a keeper because it is good in low light..
The 18-55 and the 55-200 do exactly the same as the 18-200 and do so with much less barrel distortion from 18-35 mm.
The only thing you gain with the 18-200 is you save needing to change from the 18-55 to the 55-200 lens.
You won't gain any image quality.
Your 18-55 and 55-200,
if they are in
like new condition, and you have lens hoods, are worth about $240. The 50 f/1.4 D is worth about $275 iin like new condition.
So, with all 3 of your lenses, the 18-200 owner would need to give you about $50
and the 18-200 if it is also in like new condition.
All the above depends on the condition of the lenses, and is just some examples. Your mileage may vary.
It doesn't sound like you have enough experience and knowledge to be trading camera equipment.
I recommend you hang on to what you have.