Piens makes you submit info and email, in order to get a quote, Synthplanet does not do that.

Synthplanet works as a kind of portal to different affiliated stores (probably a group of companies). One comany carries Roland, another carries Yamaha etc.

I suspect the reason for low prices in the UK is the depreciation of the pound against the Euro (now almost identical), coupled with the UK lowering the VAT percentage. (VAT is what screws European customers, vs US customers)

So, UK Digital Village carries PSR-S900 for about 1350 Euros, compared to about 1600 Euros in Thomann.