DP (not upright) new or used for wife

[Gill the Piano]

When I read your subject title I thought you were offering a swap !!
French prices will probably be cheaper as they are afflicted with the euro...are there no French websites dealing with electric keyboards? From my exceedingly limited experience of them, I believe digital pianos are far more than 500 quid; you might get a second-hand one, but then you'd need to ask WHY it was secxond-hand, as repairs and replacement parts are difficult if not impossible on older ones.
However, for that money you'd probably get a fairly reasonable real piano!

[PianoFifty]

I am looking for a digital piano, not upright i.e. she can put on her lap

Any reason for this? It would restrict her freedom to play, I would have thought, and narrow the choice down quite a bit.

Harmony Central has a database of just about every electronic keyboard made, and user reviews, which you might find interesting. Here's the link: http://www.harmony-central.com/Synth/Data/