If I come across a good deal on live rock, can I just store it in a bin of some kind, in saltwater? Would it be destroyed permanently if I stored it out of water completely?
It would not be destroyed, but it would not retain the life and beneficial bacteria for which you are paying a lot of money for.
Store it in a bin with saltwater, a powerhead and a heater and it will be fine. Dried out rock will eventually reseed itself in a new tank, but the process will take longer.
Even putting it in a container with saltwater, and a heater and a powerhead doesn't guarantee it will stay live, if you don't have any nitrates the bacteria will die back and you'll get a mini cycle as you add fish...the best scenario is to put something that will keep the cycle going in with the rock.
Depends on definition of alive...
Bacterially cultured alone (white rock breaks down ammonia and nitrite)
Then add coralline algae...
Then maybe a billion different critters:)
If you dry it you almost may as well bleach it (yet the coralline algae looks good).
It will also have organic left in it which will have to decompose.
The more life you have or want to keep alive...the more you have to baby it...
Bacteria can survive on flow and feeding (water change for nitrates) alone (at least down to about 65 degrees F - and I'm sure below). You can feed just regular fish flakes. Mine sits on my floor in two tubs...it was bleached...i put in water ...added flow...then started feeding...cycled in about 6 weeks (within a stocked fishroom) or so...
My experience (LFS employee) is just make sure if you throw in some food...everything turns to nitrates with no hint of ammonia or nitrite...and it should be good rock for your tank
Good to know that dry rock is still ok, i picked up a bunch on the cheap. Whats the best way to get it live again? Thx
Best advice is to put it in a covered bin with heater and powehead. Do weekly 100% waterchanges until the cycle has finished. After that just keep up with routine water changes until you're ready to use it. If its dry and completely devoid of life. You'll have to add small chunk of nice live rock to get it going.