Yes, you can buy just the tape with crows sounds. There are not many sounds of the owl on the tape, just a few hoots, then its all crows cawing like crazy. Probably even find a CD these days. The owl is number one enemy of crows. I don't think owls could care less about crows but the crows hate owls and other predator birds.
I have found that the shooting is good for so long. Then you have to move. Bobcat is correct, a wounded crow flopping around is the best decoy there is. Even a silouette laying on the ground helps.
When does crow season end? I was thinking end of January, but haven't looked this year.
Jason, where you located? Some stores like K's Merchandise, finer local hunting goods shops and mail order catalogs have the cassttes or CD's.
Don't mess with a call when you can buy a cassette tape for same money.
I'm sure some older folks on here can give you a recipe for crow. Sounds like one of those stories granddad would tell you. "Back in '34 we didn't have any food, had to shoot sparrows and crows for dinner each day."
Good luck