There is a reason for the price,
It's because of the reeds. They have a very special profile and are made from bronze or something simular to that. So each read has toe be shaped manually. This makes them very expensive.
I will stick with a known winner, good ole cajun music here in the heart of cajun country. pine leaf boys are nominated in 6 of 7 awards for the "cajun" grammy's down here in august
I play a vintage twenty key Lachenal concertina, mainly for things like Christmas carols, hymns and children's songs. It goes real well with my Dickens on the Strand costume. It has it's place, but like you, life has not been the same after discovering the Cajun accordion.
I know what you mean about certain songs are a good match for certain instuments. One of the ladies in out little music group plays piano accordion. She can play a slow Aire or Irish waltz so sweet you can smell the Honeysuckle.
I think that is why the Cajun accordion sounds so good, it evolved with the players and the music.
there is a very fine irish cd with concertina and button accordion, called "the lonely stranded band" featuring Charlie Piggot and a lady concertina player. Really fascinating. So, if you had an overdose of cajun, I can recommend this. (also very fine Irish singing too)