I have the answer on the price difference - apparently there is a "glitch" in Prestashop site regarding the handling of GBP - which is pretty damn bad as far as I am concerned and if it was the UK I would be reporting to Trading Standards. If you switch to Euros (the setting is way down at the bottom of the page where you click to purchase - there is a choice of Euro/dollars/GBP) the additional amount is NOT added and also the product appears cheaper! I'm not blaming Brexit or anything but it certainly appears a bit naughty to me!
This answer has come from another source - Prestashop still have not responded to my query so, as with so many other things, they obviously don't give a ****! (insert expletive of your choice)
I was/am a huge fan of Prestashop since I came across it 8 years ago when I needed to build a web-site for my new business venture and I'm now on my 4th but I'm not enjoying it this time not one little bit. Totally agree with your last para, I purchased a company with a Wix site - it was a nightmare just trying to get "my" pictures out of them.