Postage and VAT are not the problem to ship from non-UE countries o France. It's anyway the same price that I'd pay when buying from inside UE.
But the delivery company who collects the VAT and, depending on the case, the customs taxes is selling this service a very high price.
Imagine buying these 4 injectors connectors:
7,75£ is 9,15€
Plus 3,50£ for delivery is plus 4,13€
So 13,29€.
There are no custom fares from UK but VAT: +20%
So 15,948€ (you can ask a refund for this)
The delivery company charges 16 to 17€ to collect VAT, whatever the amount is...this "service" doubles the price for small amounts like this, at aprox.32€ (28 with a TVA refund). You don't pay? So there's no delivery.
Theoretically you should be able to declare and pay yourself VAT, but it's almost impossible unless you carry your own goods at the physical border, or you are a company with huge VAT amounts to pay. Most of public offices are closed to individuals.
If I buy at Q-Tech, I'll pay the 4 connectors 23,26€ delivered.
I used to buy (and sell) a lot of parts in UK, trading with Motorworks, Motobins, and Hitchcocks motorcycles.
I don't do no more since Brexit.