A couple of other things, after seeing folks mention pan liners (I assume the plastic ones?)....
Not sure plastic will hold up with the heat? Though, I admit I've never tried it.
As far as the cost of the aluminum pans, especially if doubling up, this is why I by cases of them at RD. Lots of savings that way. Granted, I do some catering and large cooks and all, but for the money I spend for 100 1/2 pans, it's way worth the initial cost in the long run.