Hi, I’m looking for a cheap/cheap-ish Eb whistle for a recording session - recommendations welcome!
My favourite Eb is my Killarney head (came with the Killarney D body) with a generation Eb body. Tuneable as well, you just need to use a bit of plumbers PFTE tape to make the joint solid. http://www.killarneywhistle.com 
Susatos aren’t the cheapest, but cheap-ish, as you say.+
Mack Hoover Whitecap on a Generation tube. Fun to play and I have found it very easy to record.
I’d second the Mack Hoover Whitecap on a Generation tube. Inexpensive with a good strong headpiece and a very nice tone.
The best Eb whistle I’ve ever played is a D Killarney head I stuck onto a brass tube from Ace Hardware and drilled some holes in. Killarney has a great headjoint design (licensed from Sindt or a knock-off?) but their stock tubes are just atrocious. I think the Killarney really wanted to be in Eb with the bore-to-length ratio, because the notes really “pop” on the Eb. Try it- it’ll take a few tubes to dial it in, but it’s totally worth it.
Killarney makes an Eb, too, although it is their nickel tube.
Be sure to check out the Dixon trad whistles too. When i got mine they were about $30-US. Good volume, articulation, and none of the intonation problems of his standard D whistles.
I did try a Dixon Eb last week - the one I tried seemed somewhat shrill although it may just be a bad one I tried (I’d expect cheaper makes to be variable in quality), but it was a bit too unpleasant for my liking (the E Dixon that I have actually sounds a bit smoother). Would love to try out a Susato but there’s no shop I’ve come across in London which has one. I’ll have to bite the bullet and get one soon as the session’s in a week and a half or so.