I am also using Gravity Forms Product Add On as well to add additional costs/options to products on a Woocommerce site.
No changing lines: $0.00
1 changing line: $3.50
2 changing lines: $5.50
3 changing lines: $7.25
4 changing lines: $8.75
There wouldn't be more than 4 changing lines that the user would input out of the 10. I imagine you could "count" the total number changing lines selected and depending on that number, add the cost
Now the exciting stuff... What the form above will be doing is acting as a template (per say). On the same page as this form would be a drop down with 1-10. If the user chooses, let's say 5 and clicks the "next" button, 5 exactly the same forms, just like the one we just created will be on the next page. This is where the Pre Render would come into play. Also, the value or cost from from the changing line radio buttons would show as well. So in this case, 5 times the number of total changing lines.
If interested, I can go in to more detail via email/phone. Also, 8-9 similar types of option forms coming in the next week that I know I will need to job out as well.
Contact Email: firstname.lastname@example.org
Date needed: ASAP on this first form