choosing a flute for Irish music

Having chosen to go the Irish flute route, meaning an older style conical bore flute:

If you want to start practicing and playing irish tunes without putting out a whole lot of money, get a pennywhistle and start playing. 90% or so of all tunes can be done on the whistle, and the fingerings are the same as on a flute.

Keys or no keys?

The next step would be to get a keyless flute. There are a few available, and the good makers usually offer a keyless version of their keyed flutes, for considerably less money than a full 8-key instrument. The fingerings are the same as on the pennywhistle. With many of them you can 'fake' a G# and the F-natural well, by half-holing.

Getting into simple-system flutes with keys however, the important ones for Irish music more or less in order are the F-natural (it is nice to have both of them), the G#, the C and the B-flat. A C-foot is nice for the occasional low C (pretty rare). Probably the least used key is the Eb.

here are some samples from recent ebay auctions:
a nice Sam Murray flute with 4 keys

a full 8-key instrument by Grintner

keyless flute by M&E