Yes, I have.....but you probably mean imported to the UK. As someone living in the Netherlands sofar I haven't been taxed for importing it......yet. But I have heard about people getting hit with VAT sometimes close to a year after the fact. Anyway on "coins" and "coin bars" I have just payed spot + premiums (depending on the coins from 10 to about 100% percent above spot), insurance during travel (between 0,5 and 2,5% off the buying price) and shipping costs. I tend to pick dealers and suppliers with fixed delivery costs. Depending on the size of purchase and the package(s) usually between 5 and 50 euro's.
I don't have any info on importing bars. I think over here they are taxed with 21% extra VAT. That makes the "investment" even from a collector point of view very, very, very costly. Storing them in the country you purchased them is a more cost efficient method but the question is if you have enough faith in the stability of the system and the nation it is in to be able to get / trade it if you need to.