Alternative to Marsala?
Consider using:


1/4 c. white wine + 1 tsp brandy ... or go as high as a 2:1 wine to brandy ratio. I like this substitution best personally.
1/4 c. white grape juice + 1 tsp brandy
Madeira wine - I've heard you can use this, but I never have
Port - again, I've heard it but not used it
Brandy alone, though I find this to be a bit strong