Assuming the axles are complete and in good shape (i.e. do not need to be rebuilt and ready to bolt in) it's not that bad of a deal.
The 14-bolt should have a Detroit Locker, which would cost you around $500 new. If you really wanted 4.56 gears that would probably cost $300-$400 just for parts to regear a pair of axles (4.56 do not seem to be that common in civvy versions, but are out there). Taking that into account you have $1,100 in just the axles. You could probably by a D60/14-bolt, 4.10 gear, open diff combo all day long for $1,100.
You can find better deals out there but it requires quite a bit of work and some time. Don't expect to find $300 Dana 60's on Craiglist left and right as they axles simply are not that common and a lot of people know what they have.
I spent around a year looking for a Dana 60 front for a reasonable price and finally found a ragged out complete and running K30 for $750 through one of the guy's in my off-road club (it was his uncle's). A friend of mine is a semi-professional picker (not officially but he makes a LOT of extra money buying and reselling stuff). Bet he's bought and sold 20 front D60's of all versions over the last several years. Never paid more than $500 for any of them and probably averaged $250/axle overall. He resells them for $700-$850 and that is with him wanting to turn them around within a week or so. The $850 one was the coveted and most rare '78-'79 Ford high pinion version with a Detroit Locker with the overall axle being in really good shape, and it still took him a couple weeks to get rid of it.