Couldn't you use Aveeno ('human' shampoo), or even the oatmeal treatment that Aveeno makes for a bath soak (my mom got it for me when I had chickenpox)?

I had a vet tell me that most dog shampoos are just overpriced versions of people shampoos anyway. (for example, he recommended using Johnson'n'Johnson baby shampoo on my kitten because it was gentle and 'balanced'); he himself uses Dawn dishwashing detergent to bathe dogs when they are too dirty or oily to treat (yes, some poor mis-informed people around us use old diesel fuel, etc. as a home remedy flea dip ) and has never had any problems with allergies to the soaps or anything.

I'm interested in this topic, too and will watch to see what other people recommend, since my girls have some mild allergies...which could get worse, I suppose.