If that's a px-10e, it's worth some decent money. These bikes have a serious cult following, and real francophile cyclists can tell you all about the various models, variants, best/worst years, etc.
I'm not a real francophile cyclist, so I'm afraid i can't help much. I can point you in this direction:
http://www.classicrendezvous.com/France/bicycles/Peugeot/PX10_history.htm
Of note: the page mentions that many folks misidentify their Pug as a px-10, and how it's easy b/c Peugeot offered many similar models, many in 531, etc. It has been my experience that a lot of these are misidentified, and unscrupulous sellers will attempt to capitalize on the px-10's cult status, as well as the fact that for much of the 60s and most of the 70s, Peugeot didn't put any decals on the frames to identify the model.
Also of note: the bike pictured does have the black plain Nervex head lugs, with the other lugs being white, and that is in fact consistent with a '72 px-10e. so, yeah, it might be the real deal.
I agree with maurius, though: go to bikeforums.net on the classic&vintage appraisal forum. They'll know what it is, and give you a value on the conservative/miserly side of the scale. Just make sure yuou put up pics that don't reveal the bike's ad online. If that's a real px-10e at a nice price, someone will poach it on you.
Good luck!
-Rob