Ability for Addons?

Hi,

I would like to know if possible a product can have addons as an option? So when someone buys something, can they then have a 'design fee' option which would add £x to the price? Or they could order a 'file check' service for printing for example for an additional £.2.50.. Ideally this would be part of the checkout process not part of the characteristics as the product already has a large number of variants so it would be hard to administer these options as variants and would make the website quite messy in the backend.

This would be something like the shipping process where they can check which option they would like and it adjusts the price, it would be good if i could have another instance of the shipping for these addons such as a 'file check' service

Thanks

Alex

Thank you!