As far as inexpensive whistles go, I'd recommend one of the older heavy wall Dixon C's, with the long head (not the new ones being sold that use a dixon trad head). Here is an example of a nice one:
http://www.irishflutestore.com/dixon-heavy-wall-brass-c It is not very loud at all (nor super quiet, either), but it plays easily, nice octave transitions, good balance between the octaves without being too loud in the highest notes, and overall very nice, and imo sounds like a proper whistle. I have no stake in the website or sale of the whistle, that just happens to be an example I found online.
Freeman's whistles are also very very nice, though I really only prefer his D and Eb whistles. His bluebird and blackbird D and Eb whistles are especially nice. It depends on taste, but I don't care for the tone in the lower octave of my Blackbird C or tweaked Generation Bb. I'd rather play an untweaked Gen Bb (or one tweaked only with poster putty), or the aforementioned old dixon C over either one. I think the lower octave on his C and Bb that I own don't have enough roundness to the tone. I'm clearly in the minority, as many people do love his Bb and C whistles, so perhaps you would as well. It can't hurt try one. I will say the upper octave on all of his whistles sounds very nice and sweet, regardless of key, and none of them are bad whistles.
I'd hold off on the Susato C until you are back in the groove with Irish music.
Just my opinions, though. Any whistle is a step up from no whistle, so the important thing is to just obtain one and play it, regardless of what you choose. Generation Bb's are cheap enough and usually of great quality compared to other cheap whistles, so it never hurts to pick one of those up as well for playing around the house.
