There was a published study for the PLC done a few years back showiong the average spend of the day tripper (once a season or once a lifetime) being STG£100+ per game.
I was in Manchester a few years back and did the Museum tour etc and met a local guy (City fan obviously) who was bringing 3 Japanese tourists around. There was no football on but they flew from Tokyo to see Manchester and the Museum/stadium and bought half the Megastore. Apparently the club even do very well from people like that.
Hope it all ends up in court - great story. Come on the Irish guys!!!!!