Product Add-Ons: Change price percentage based on variation

Hey all.

I am using Booster Pro for product add ons and it works great, but we have a unique scenario (well maybe not unique but here we go)

I have a pizza. it comes in three sizes (small, medium, large). I have extra toppings (add-ons), but we need the price to vary based on the size.

e.g. If I select large pizza, each extra topping (add-on) is $4.25. If I select a medium pizza, each extra topping(add-on) is $3.75 and an extra topping for a small is $3.25 – using percentages to calculate the add-on price doesn’t work out for us.

Any advice or custom solution appreciated. If anyone thinks they can custom code this in for us, please let me know.

Thanks