There are ways to straighten them and they have been written up on this forum.
I am even lucky enough to have come across a saw tensioning hammer (or a file
cutter’s hammer - much the same) but I still had no luck in the moderate amount
of time I spent trying to do it.

There are so many good, straight saws out there I don't think you should bother
with bent or kinked saws.  Look for saws that are not pitted near the teeth -
easy enough to clean surface rust.  Consider that shorter saws - 22” and 24” -
are really handy in the shop if you aren’t ripping or crosscutting big pieces.

Sharpening is no where near as hard as it looks at first.  You can get an
acceptable sharpening in 30-40 minutes your first try.  And it is not necessary
that all the teeth be identical, just close.  If a saw wanders, a quick stoning
down the length of the teeth on the more aggressive side will fix it.

Most saws were made by the big 3 despite their etches, so almost anything of a
vintage look will be good.  Get one with the number of ppi you would like as it
is a PIA to change it, but easy to follow what is there.

A comfortable handle is very important.  Gluing on a new horn and shaping with
rasps and files in not too demanding and a good thing to practice skills on.

This works unless you live someplace where there are no used tools - here in the
mid-Atlantic we have to be careful not to trip over them
 
Ed Minch