550D, 600D, 50D: which EOS

Hi girls,

I've just sold my 450D and I'm going to get a new Canon.
I'm not intersteste in video.
Which one to go for?
BRAND NEW 500D = 450 euro
BRAND NEW 600D = 500 euro
USED 50D (1 year warranty remaining) = 600 euro

I'd go for the 50D but it seems to be a little overpriced.

I haven't seen it yet, the seller says it's in perfect shape, no scatches, shutter

What's your opinion?
Thanks in advance.
Gico