SRS used to be a great grey import source but nowadays they are an official dealer for Pentax, so they have to sell the body at the RRP.
However they do some very valuable bundles with lenses. I bought my K1 and 24-70 2.8 from SRS for a lot less than my local shop, Park Cameras. But the other big reason was that Park Cameras had only an "old" specimen in stock (been sitting there for months) while SRS had fresh stock and I wanted that, to avoid some specific early issues which are common with Pentax.
Import from Hong Kong or the USA used to work because the vendors would gift-wrap the box and declare $20 value
Most of the time you would get away with it and when you didn't there was no net cost over the UK. But nowadays the Post Office knows that collecting import duty and VAT and charging upwards of £8 each time for doing it is a nice income stream for them, and it is really organised to assess practically every package. I haven't seen anything get through for ages.