The paint and decals appear to be in decent condition, though it is difficult to be certain from the photographs. Original paint and decals = a big plus.
I am concerned about the incorrect handlebar stem. You'd want to replace that with something of the correct diameter and check for damage to the steerer tube. Also check to see that both the stem and the seatpost will move freely, before purchasing the bike.
The rear derailleur appears to be a replacement, perhaps a SunTour. You want to check the rear drive side dropout to see how the new derailleur was mounted and if the Simplex integral hanger was damaged or removed.
The hub skewers are the older style Simplex, suggesting an earlier rather than later date for the wheels.
The pricing on Peugeot PX-10 has been all over the place. I've seen them below $200 and up in the stratosphere as Randy mentioned.
This one, if you have been looking a while and it is in your size and you like the overall condition, perhaps $200-300 on a good day. Budget extra dollars for the necessary replacement parts (brakes/brake levers, derailleur, shift levers, bar and stem, freewheel) if your goal is to make it factory stock.