Having looked at the O'Neill's website, it seems I'm looking specifically for an O'Neill's "corporate wear" polo shirt, not a GAA jersey after all. Apologies for my ignorance. I cannot see a way to price these online at oneill's site. I've seen them in the shops for €40 and I'm curious to know if they are available cheaper anywhere else.
Thanks BB for the leads. If I find any of the items you're looking for, I'll post info back here. Good luck on your search.