Product Add-Ons

It would be good if there is possibility to set the price dinamically by products’ variations.
Basically if I have a variable product (for example, variation in size) but I cannot set the price of a possible addon options added to the product.

Ex. If I sell a picture, and this picture has 2 size 20 “x20” and 50 “x50”.
Then I want to add a frame by product addons. Of course if I chose the first option (20×20) the frame will have a price, but if I choose the second option (50×50) the frame will have a different cost.
there is no way to set the price in order to change dinamically to adapt to products’ variations.