[96capricemgr]

A signature to let us know what your car is would help a lot.

$250 is probably average labor for a gear install, going to need bearings and seals beyond that. A fesh posi would be a good idea too. Might find a worn axle shaft or two.
Depending on year you might need an ABS reluctor.

Speedo needs to be addressed, what that takes depends on year.

A junkyard axle is an option, never really sure what you will find wear wise though.

For the effort I would do 3.42s.

I have had between my 3 b-bodies 2.56(wagon), 2.93(sedan and wagon), 3.42/3.73/4.10 in the sedan. For a pure driver 3.42s are the winner, they were great, only changed them for the track.