I fully second Ventura's message: take a vacation near Castelfidardo and make appointments to visit several factories and try instruments. Hotel Parco is indeed a good place to stay. It's in the spot where the Crucianelli factory used to be (burned down in the early 70's).
Good quality new accordions (full size 4 voice, cassotto, 41/120, no melody bass) will set you back roughly anywhere between about 7.000 and 12.000. Accordions have become more and more expensive at a rate that exceeds inflation. A good place to compare accordions closer to you was the Frankfurter Musikmesse, but alas this has not survived the Covid shutdown period.
You won't find an Excelsior factory as this company was absorbed by Pigini. (That also brought down the Hohner Morino line as the N and S series were made by Excelsior. Newer Morino's were made by Pigini and just were not the same.) You will see that Bugari and Zero Sette are in fact the same factory. There are other factories that make several brands that were at some point in term independent. Victoria is worth a look, bang in the center of the town. And you must visit Beltuna as this is undoubtedly the most innovative accordion maker. They are also possibly the most expensive.
There are several more small accordion builders which you can find just by following sign posts you find along the streets.
The museum is nice to see many very old instruments, but you cannot try any of them. (They just have two recent accordions to try.)
If you want to find something for less than 5.000 you will only be disappointed when you look at new instruments. You can get good used accordions for under 5.000 but to find them Castelfidardo is not the place to be any more than anywhere else...
beautiful!!! I can see you have visited some great places in Brazil, Tom
I have a Cangaceiro hat as well back at my parents home in Sao Paulo. If you are ever there btw, don't forget to visit "Canto da Ema" (https://www.cantodaema.com.br/pt-br/). Mestrinho plays live forró with his Giulietti there at least once a month.