There is no way to tell the values by brand names as OP described them.
Brand names and models mean little as there are thousands of different
ones. From what little I can see here, these accordions are the sort you
should sell on ebay as is, without making any claim as to the condition
and get whatever you can, and don't offer returns.
Opening them up is something a technician could do, but you can tell if
they need reed work by just playing each note one by one and listening
for any odd noises or dead notes. Usually it does not pay to have them
repaired, because few people know enough about how to play them, except
as a toy to play simple tunes, and many that you find are shrunk-down
student instruments, that are like 120 bas accordions made to sell to
children back in the 50's and 60's when people could actually make money
running accordion schools.
if you posted a few photos, I could estimate value parameters for you.