wanted-apple iphone 4s for 300 pounds ?

hello there. I m looking for iphone 4s for 300 pounds. preferably black. unlocked or on networks o2,orange,vodaphone. in brand new condition or used but in pristine condition. should be in full working order and fault free. Really desperate so please let me know. I will pay upto 350 pounds in cash but no more than 350. thanks