When buying things now on eBay UK from Europe, the custom charges never seem to be fixed or related to the price of the item, so there can be some nasty surprises, especially for smaller objects where the custom fees are sometimes higher than the price of the object. That is probably because the sum to be paid at customs is calculated by eBay themselves. There is very often 20% VAT added on to the total sum now too, which isn't always indicated until you go to pay.
British customs can be a little difficult too with incoming goods & may hold the parcel without informing either the sender or recipient & when you contact them to see if it is held up, they'll likely inform you there are more custom charges to pay.
On the other hand, things can go smoothly & there are no unpleasant surprises.