I'm making a "calculator" of sorts in excel and I am stuck on one last part.

I want to type in the product, and when I type that product in I want it to
equal a dollar amount , and a different amount for a different product, etc.


I also need it to to change the formula used at the end to create the total
amount..

Example:
This is the formula I use at the end to get the total.
=SUM((D17*Sheet2!D17)/1000*F17+(G17*0.66)+(H17*0.05))

I need the formula to change at the part where it says "Sheet2!D17" as that
is the price.

When I type "80" in the product part, I want that to equal $7, "55" = $5.50,
"40"=$4

Can any body please help me?