That's true, forgot about that. Come to think of it my Crackphone kit managed to sneak through when usually anything over $100 in value gets held for duty ransom.
There seem to be a couple of oddities in the uk post system a couple of things can really help with fees on the customers end.
For a kit the customs form should read the parts value inside the box which I think is the case when a second party like Massdrop becomes involved they list the full value.
This can be a massive saving
It helps if buying from the US if you can request standard USPS shipping this takes in y experience just a few days longer but has several advantages
1 Items normally sail through customs
2 Is often delivered by your postman
3 Does not attract a handling fee
The more expensive international post options
Arrive quickly but can get stuck in customs for a long time over a week is not uncommon!
Attract a handling fee by the post office of £8 or handling fee of £19 from Parcel Force if sent via USPS Global Express.
It starts to mount up real quick especially once duty and vat/tax are added. I have had no problems with the plain old USPS shipping and always ask for it now.
http://www.dutycalculator.com/new-import-duty-and-tax-calculation/