II agree it could be a PH10, but t's definitely not a 531 frame. I should be Peugeot's "Carbolite 103" or "HLE" tubing, not as good as 531 tubing but very good "basic" bicycle frame tubing none the less.
The $125 price is a bit steep if this bike is not in mint/new condition (although it looks very clean, I think you can negotiate the price at just below or at 100 bucks to be more in line to what the bike is at the open market.
Frankly, I think it could be worth more if the derailleurs and double crank rings were mounted back on the bike.
JMO's

Chombi