In my area, at local aquarium society auctions, depending on what people are breeding, you could get a bag of 10 young dovii, or managuense for less than $5.
I had beani spawning last year, and was getting $3 each, and when I had haitiensus and tetracanthus (Cubans) spawning a few years ago, I had a hard time giving them away.
If they were 1 year old or older, they might fetch a better price, but then you need many and large grow out tanks.
As far as what might get you real money,
the other Cuban, Nandopsis ramsdeni, last time I saw them at $300 each
or the African Heterochromis multidens.
I just saw a group of 6 x 2inch H multidens for sale, for $1500. (yes, one thousand five hundred)
These are very specialized fish, and may have a very selected audience though.
