For simplicitys sake i would reccomend a D4s off Amazon...
I think you'd be wasting your time and money trying to order any Fiido off either Amazon or Alibaba (or anywhere else for that matter)... the order still has to be routed and shipped through one of Fiido's own distribution centres - which Fiido just aren't doing to UK customers right now because of Brexit complications (extra taxes, import paperwork etc - they've told me so).
Fiido currently say they're only supplying direct or through their approved people - Banggood, Gearbest, or a very small handful of appointed dealers as listed on Fiido's own website (Fiido have a beef with non-approved suppliers, which, having looked, both of those seem to be).
The Amazon sellers price of £740 is in any case stupid... Fiido's direct price today for a D4S is/would be £504 inc UK shipping, but since Brexit, and until they have their own UK stock and distribution in place, you'll just have to wait. IMHO, at £504ish it's a really good buy. At £740 - even if someone had a few imported pre-Brexit models kicking about - it's a bit rich given the alternatives (the D11 for example).