How much would it cost to get a gas tank drained out for a 95 Mustang at a shop?

I accidently put mixed gas that was a lil under a gallon in my tank..and my car wouldn't start...my friend help me take the tank off and get all the gas out but won't help me put it back on and I don't have the tools..how much would it cost at a shop for them to put my gas tank back on?