Droogs, when I bought my Excali in Germany and imported it into Switzerland I was pleased with how low the import duty was. I can't remember off hand (I could look it up if you really want to know) but it was about 5 or 6% I seem to remember.
I don't even remember how much I paid in total, but again can look it up if you want to know - I just remember it was quite a bit cheaper than buying it from my local dealer.
Of course it's actually a quite complicated calculation - you first knock off the VAT from the retail price (in Germany 19%; in the UK 20% now I think?); add on the cost of Swiss import duty (as above); then also add on the Swiss VAT (7.9%). Then also add the cost of shipping (which didn't apply in my Excali case 'cos I went to Germany to pick it up). But I THINK I'm right in saying that if you in UK buy from another EU country then the bit above about removing and replacing VAT doesn't apply.
And just to make matters "easier" (!) you have to add in exchange rate differences (Euro to Swiss Franc in this case; or of course £ to Euro if it's your calculation).
As above, it DID work out cheaper than if I had bought it in Switzerland through the local dealer, but, as above, it's a complicated calculation which due to exchange rate fluctuations needs to be done at the time you're doing the buying, not "months" in advance.
I'd also add that for me anyway, it's not worth all the hassle of importing if I'm buying just "a few quids worth" of stuff. The only time I buy from overseas is A) if it's expensive stuff (say, at least 500 quid), or B) if it's not available here (e.g. Kreg).
In general terms though, you're dead right, just about everything you buy here (e.g. foodstuffs, toiletries, medicines, just about every day-to-day item, is much dearer here than it is in neighbouring countries - and I AM talking about exactly the same product/brand/ packet size BTW). But to a large extent, that's not due to import duty - nor to our non-membership of the EU (but I'm NOT going there)!
HTH
AES