With the possible exception of Esoterica, the stuff that's still in production isn't as difficult to get as most people believe. You just have to actually order it when it comes into stock.
For stuff out of production I see no real need to chase something with a permanently limited supply even though I have chased a few. The ones I did chase I just got a few tins so I could try it and to 1, see if I actually like it and 2, find something in the same vein that I could enjoy, replenish, and forget about the old unicorn.
Of the out of production stuff I've tried I give an enthusiastic "meh". Sure, it's actually pretty good stuff but there's better out there. Saying that it is not exactly the same does not speak to "better" or "worse", it's simply not the same. I don't care that it's not the "same". I think far to many people view some of these blends with the rose colored glasses of nostalgia and over-hype them.
The only remaining unicorn on my list is Motzek Strang.