yep, there are a couple of firms i've nearly bought things off who charged, say £5 for postage, but it was gonna be maybe £60 to Northern Ireland!!! but theni e-mailed a firm once asking was it any extra for here, as their site stated Mainland, and he said that as far as the post office is concerned Northern Ireland IS mainland! it is included as part of the UK and postage should cost the same.
i think a lot of people just can't be bothered going to any extra effort so just make it that we won't bother them.