Unless there are major rust or dented barrel issues, I'd say go for it. Worst case is you could easily sell it and get your $ back if not make a few $ off of it.
Thanks for the help guys. The $50 is not including shipping so I still have to negotiate a final price once I get an estimate. Hopefully shipping from PA wont be too bad to kill this deal
I have a new 870 express I bought a few months ago. I bought a used 28 inch barrel at the Marlboro gun show a few weeks ago for $50 and thought I got a good deal. It fits great and after I cleaned it it looks good too. I was told all 870 barrel are the same, not sure, but this worked well for me