As Ireland's need would be purely defensive and to remain clear of the political consequences of being overtly tied to the UK or US, I would have thought that the natural choice would be to lease a number of Saab Gripens from Sweden, another neutral EU Member State.
Gripen is also cleared against the A310MRTT for AAR, so perhaps Omega Air might consider taking over a couple of Luftwaffe tanker transports when they leave service in the next couple of years? I'm sure Ulick could negotiate a good deal!