Martin
Guys make a feature to handle option prices in Shopify. The way you made it work in Woocommerce is great.
The way you made the work-around on this article
https://help.customily.com/hc/en-us/articles/15743447086363-How-to-charge-extra-for-the-personalizations
is not the best work-around.. why?
  1. ) Customer will be confused, "why do I have two products in my cart when I only ordered one?"
2.) Customer will be able to REMOVE the personalization product in cart.. which will result in them ordering for a cheaper price and will result in our loss.
3.) Customer will write to our support, which will increase our agents workload for no necessary reason.