Never bought that item so I can't comment directly on it, but I generally figure on around 3% of purchase price for import duty, plus VAT at 20% of the purchase price AND delivery cost. VAT is charged on postal fees as well as the items value at point of purchase, and depending on the item value you may also get hit for customs duty.
As a basic rule I usually work on 25 - 30% over the total price on anything of value.
This is from the HM Revenue & Customs site:
Goods Value*
£0.01 to £15
No customs duty
No Import VAT
Goods Value*
£15.01 to £135
No customs duty
Import VAT due
Goods Value*
£135.01 and greater
Customs duty due, but waived if the amount calculated due is less than £9
Import VAT due
I bring quite a lot of stuff over, mainly Seiko and Omega watches, and 30% is my overall rule of thumb and it usually comes in at a little less than that.
Not sure if that helps or not, but there we are.