You can usually purchase merchandise online at the IFA website, but they are experiencing technical difficulties at the moment! For future reference anyhow... http://www.irishfa.com/index/articles.php?id=1365&page=Shop+Announcement
Just found this as well... http://www.subsidesports.com/uk/sto...0065&cid=135&brc=&red=product_list.jsp?id=135, That shirt is very smart. The picture doesn't do it justice to be fair.
JJB Sports are the official stockists apart from the IFA http://www.jjbsports.com/detailfash.php?type=FASH&code=87101301 http://www.jjbsports.com/detailfash.php?type=FASH&code=59520301 you could always go for a vintage replica from Toffs http://www.toffs.com/icat/nireland good luck and enjoy hope they post to the states
Sometimes there are nice Norn Iron tops on Ebay. On ourweecountry.co.uk there is a "for sale" thread.