This thread and some other similar instrument-based conversations have been a terrific money saving tool for me. It can be easy to get caught up in the wonder of buying shiny new accordions with all the special features. Yet I rarely find that the daydream is matched by the reality, and even the effect of Guidobaldi reeds (with voices like flutes) encased within a precious cassotto of aged Wisconsin maple, doesn't quite soothe the shock of the invoice that accompanies said lovingly crafted accordion.
Now, I just checked and apparently accordions are not on the commodity list alongside copper, wheat, Rolex Submariners and solid gold... so sadly the Excelsior AC doesn't stand for Asset Class.

Yes, we accordionists must suffer for our art in more than one way! So I must confess now that I enjoy talking, listening and playing accordions considerably more than collecting them.
I currently own two accordions, an old 4 voice musette Bugari PA and a Pigini classical PA - both mid level but solid quality. They are all I need... I guess I could replace both with one five voice accordion, but the weight of the five voice would make me tetchy. So, for the time being I'll stick to what I have.
If I can get my act together and my playing improves significantly on free bass, then I probably will replace my Pigini with something more fancy, with an extra bell and maybe two whistles. A compact 4 voice Zero Sette converter would be nice, but I can't quite decide whether to go 45 keys or stick with 41 keys. I am not convinced I would actually need the extra 4 notes.
Anyway. I'm off to practice my accordion for a while. See y'all later.
Oh wait, I forgot to say... very interesting point Dan:
The Serenellini above is a good accordion for a variety of world music styles. I also think the value for money in
standard bass accordions is to be found in the small family run businesses like Serenellini, Siwa & Figli, Fisitalia, Giustozzi or
@Tom's Piatanesi.
However, for free bass, well that's a different ball game - with different technologies and different sounds. I would look for the big free bass specialists (Pigini, Bugari etc). For example, if I wanted to hear some Zolotaryov I would like it on a Jupiter or AKKO bayan... and if I want some Renaissance music I would enjoy it on a big Italian concert accordion. Your preferences will almost certainly differ...
Out of interest, any thoughts on the tone of this accordion below... It's very distinctive! I like it for the style it's playing, but maybe not for a Highland Barn Dance...
Riccardo Centazzo playing Frescobaldi on a Zero Sette concert accordion (with 5 voices).