I've ordered stuff from the US several times and previously haven't experienced any difficulties.

However on Saturday our postie popped a card through the letterbox telling me I had to go collect my package and pay £11.52 duty on it (and bring exact change, the fuckers). The items I had ordered were $30, which according to the documentation was $12 over the threshold. They then said I had to pay £3.52 duty on it (fair enough) and an £8 handling charge! EIGHT POUNDS! Hence I paid £11.52 duty on $12 of goods.
Previous orders have been for more than $30, maybe up to $80 with no problems. I'm now scared of ordering stuff again.

What's the deal? What are the chances of getting stung again? Pretty boring, huh?