I've set up a fabric shop, which requires free sample purchasing. I've implemented this without issue using on the fly products for each fabric. However, the client now requires that after x amount of samples have been added (across all products) each additional sample should be charged.
I've spent several days trawling the developer docs & internet trying to find a solution, but so far it has eluded me. Can you please confirm the correct procedure for modifying a dynamic products price which is already in the cart. I've looked at the cartthrob_update_cart_end hook and $this->core->cart - but can't seem to figure it out.