If no one has one to sell you right away, they do pop up on Ebay and other similar places from time to time. It’s easier to find a C or F, since not as many people want one. There’s a few on ebay right now, last I looked. But while you wait, I have a few tips to consider. I’m a newbie myself, but I am a few months ahead in getting whistles and trying things out. If you’re looking for some variety in that intro price level, look at a Sondery C/D plastic set, a Clarke Sweetone, or simply a new-model Generation. You can do the minor tweak on it yourself of removing the cap with hot water and filling in the cavity under the windway. Look for “how to tweak a whistle” on youtube, there are plenty of guides.
The next step up, is you might look at Dixon whistles. Those are gonna be in the, like, $60-70 dollar range, generally. DX005 or the Trad, are probably the two I’d go for for a level up. And the Dixon Trad is super cheap right now on hobgoblin usa, under $40, so that’s the one I’d go for if I were you.
But if you’re willing to put up a bit more money and get something you might really hang on to for a while, look at something like a Wild/Glenluce/Lark in the Morning/Verdant (which are, I’m pretty sure, all made in the same factory in Pakistan). They’re good, although I do hear about production issues (rarely). Or, for a slightly more confident purchase, get a Killarney or a Lir, both of which are handmade. Both of those you’d get right from the producer’s websites. Lir costs more, and I haven’t seen anyone saying Lir is better. They’re very similar. I have a Killarney and I am confident in saying that if you’re gonna be serious about learning to play the tin whistle, you won’t regret it. You’re looking at like, $100-$130 for the ones in this paragraph, except the Lir, which is 150 euros. Oh, sorry, all my prices are in USD, not canadian. But you get the idea.
I’ll let you know if I spot a vintage Generation D anywhere, though. Good luck!