Get money for propane tank?

-Only as scrap metal - and then only if it is empty.Absolutely. Look at getting $1 - $2 per gallon for the tank. This is assuming that it is still usable and has not been used for other substances like ammonia. You can try posting on craigs list or visit your local propane dealer to see what they will offer.
Just what Peter said, but most of the scrap yards will require a 1" hole to be drilled in the tank. Not a fun idea if you ask me! Drilling creates heat and sparks, Sparks + Propane= One good Youtube video for some. Not so muck for the driller.