Is there an alternative wrapping for tamales?
I've had the same problem once. The first substitute is banana leaves. But they're not easy to find either.

The second one is using big leaves of chard. Tamales will be done in the same time and you could eat the leaf if you want. I've tried it once and it came out great. 

Here it's a recipe for tamales from Michoacan made with chard. Here it is a graphic step by step recipe for tamales with chard. They are written in Spanish, let me know if you need a translator ;) 

PS. My mexican mother in law used to do it with chard.