You just have to make a choice at the end of the day, which is a pain as I often agonise! I can get an LRP sphere speedo and 5.5 motor for £140 from a place I know is good in the US, not pay shipping (I am lucky as I have family travelling there a lot) and I think thats just below the customs amount too, and in the uk thats £215 of kit as far as I can see.
So I tend to gamble, I make back the price of a full set for every 2 that I buy, if less than 1 in 2 break during the warranty I win, if more than 1 in 2 break I lose!
Having said that, I have never tried to actually ship stuff over here from the US for anything I could get in the uk, reason being by the time you add shipping/import duties, its the same price just about anyway, and at that point may as well get that UK warranty! I just get away with having things picked up for me over there.
One alternative is the far east ebay sellers (I use Tamiya's so know of a few of them) where they seem to hardly ever get stung for import (not sure if its due to dodgy forms at their end!?), and shipping is dirt cheap! However, again you need a reliable store, and also you need to watch for quirks (like 40mhz bandings being different in Hong Kong so receivers won't always work etc).
Whichever you choose though mate, good luck with it and hope nothing breaks anyway because even with a warranty its a
!
Dave