Investment should not be much of a consideration.
I'm no longer certain that there's such a thing as a "good investment" in the sense of "likely to be worth more when I sell it than when I bought it". I can't think of a single category right now where this is the case, and certainly not relatively inexpensive musical instruments.
I mean, in the scheme of things, even a $6800 Kanile'a Platinum is relatively inexpensive even compared to a standard production model guitar aimed at professional musicians. An investment instrument has to have something extrinsic to the instrument going for it, often related to who owned it, where it was played, that kind of thing.
So yeah, the value of the thing is exactly what it's worth to YOU, and that includes the pleasure of playing something beautiful.
As others have noted about the intrinsic value of anniversary models, it depends....but
@ghostrdr mentioned Kanile'a in the original post, and I gotta tell ya, those
look like they cost as much as they do. LOL
I was able to take the Kanile'a factory tour (a story for another day), and I can tell you that the Platinum series, especially here in the 25th anniversary, is not just a regular K3 with a slab of silver or whatever. This is allllll the bells and whistles, for those folks who value both bells and whistles above and beyond how an ukulele
sounds.
(for the record, I'm not the guy to comment on whether the Platinums sound any different than another high-end Kanile'a. I'm not a good enough player to extract that difference if indeed there's any to be extracted.
)
Flight is another company that's using an anniversary (their 10th) to go above and beyond. Most of their stuff tops out in the upper-mid-hundreds-ish, but their 10th anniversary series is comfortably north of $1000. The newly announced limited edition Koa model is $1300, give or take (£1,082.50 pretax at SUS, which includes free shipping to US, and yes, setup LOL). Unlike Flight's production models, the anniversary series are luthier instruments, eg, one dude, who's building in batches of 4 and 5 at a time. So the price is the scarcity of the model, the elevation of the design, and the sweat of one man's brow.
Me, I think it sounds pretty dynamite. I know I'm not the only Flight fan here, either. Knowing that the days of the $1000 Hawaiian-built koa ukulele are nearly over anyway, this price seems like a pretty decent deal for a luthier-built instrument. I've set this embed to the sound samples about halfway through, but you can go back to the beginning to get the whole pitch on why this instrument is the way it is, and why it costs what it does.