?_Green: buying a pizza place

I am looking into buying a pizzria in Norristown, Pa. The store is 8 yrs old and currently doing 7,100 week in sales. The seller is asking 175,000. I thought the value of a pizza place was weekly sales times 1 biz quater, or 13 weeks. Am I wrong in my calculation and should I be paying 175,000 for a store doing 7,100 a week.

Thanks for your help,