Gas Prices In Port Washington

My family and I went to Wisconsin Dells and I was appalled at the disparity between Port Washington's gas prices and the gas prices we saw during our 2-1/2 hour drive to the Dells.  At first I thought it was a county-wide thing, but found out differently when I went to Grafton this past weekend and discovered that gas was 8 to 9 cents cheaper at the gas stations there. 

I don't understand how Port Washington can be allowed to price gouge its citizens like this.  If you look on the news Port is consistently almost 20  to 30 cents more expensive than the national average.  Looks like I need to get my bike out because I refuse to be taken advantage of by  the local gas stations. I guess it just shows how little they think of the people that keep them in business.