Formula for a cell value with a multiplier

I'm fairly new to Excel so here goes. So I'm in sales and we offer a certain budget worth of free product per customer when we set the customer up on our services. Each product has a point value associated with it. So we are allowed to give up to 8.5 points worth of free product per customer. The multiplier is for every .5 point of product above the 8.5 point threshold we end up giving for free, then the sales rep has to pay $15.00. On the flip side, for every .5 point below the 8.5 point threshold we gain $15.00.

So the question is what would the formula look like to make the numbers read correctly in the cells? My goal would be to simply enter in the total amount of points given shown in Column A and in Column B have the cell auto populate the dollar amount +/-. The key factor is 8.5 points is the middle. Anything above I have to pay, anything below I make money. So what's the formula to make Column B read correctly based on the point value entered in Column A?

Again I'm kinda of new to Excel so I hope my question makes sense. I appreciate your help!

Example:

	A	B
1	Free Points	Point Profit +/-
2	9.5	($30.00)
3	8.0	$15.00
4	7.5	$30.00
5	9.0	($15.00)

It works perfectly except if there is no point amount entered, then it shows a dollar amount of $255 for some reason.

Sorry, I get it now. The $255.00 that show if you put no point value in the first column is the amount you would make if didn;t give the customer any new product. I get it! Thank you so much!!!