Northern Ireland is not part of the National Rail network, so i'm not sure how you can be proud of a slow train in England.
The Stansted Express service costs £26 for an Off Peak return travelcard. As I have a 16-25 railcard I can get that for £17 or £13 for the Return journey.
So, if you live in GB that journey will not cost you that much. I mean £13 return is cheap as you will get.