Somewhere between $1.00 and $1,000,000.00 per month.
Just kidding. The question you asked is difficult to give you an answer with any degree of accuracy, but you aksed for it.
Coffee shops realistically range between the $100,000 per year and up to the $2,000,000 mark. Of course the upper range would be a super high volume location in a densely populated area, so let's drop it to a little more realistic $1,000,000 upper range. If you break that down to daily sales, you are looking at a range of say about $200 or $300 a day up to about $3,000 or more a day.
Now look at the location you are looking at. Is it high foot traffic? Next to a college? Thriving business district? Competition?
All these things add up to an "average" (if there is such a thing) coffee shop doing $1000 a day.