First, I'm going to say what everyone else is too polite to say. You are a moron. Get out of the sign business before you ruin it for everyone in your area. $3.50/sf for finished banners? Wholesale, sure. But why the f&!k are you selling at wholesale to an end user? If I were one of your local wholesale clients and found that out, I'd never buy from you again, and I would damn sure take the time to find out who your other wholesale clients were and inform them of your unethical behavior.
We do wholesale work too, as well as retail. When you choose to straddle that fence, you have to be very careful not to mix the water in those ponds.
Gary