Adding physical product option w/different price without increasing inventory

Site URL: https://www.melissadinino.com/originals/quick-release

Hey everyone, I have a question for y'all. 

Has anyone figured out a way to add an option to a product (not necessarily a variant) that displays a different price for that product without increasing the inventory? My example, to clarify, is with artwork. I want to give people the option to add framing to a specific painting or buy it without. So say I have a small painting that is $500. I want to have on the page - almost like a variant - the option to buy that painting with or without framing - the option with framing being more expensive (say $600). If I do it through variants, it forces me to say there's one unit available of each. In this scenario, I would have to hope two people don't go to buy the different options at the same time, which is very possible, and if they didn't I would need to watch my store like a hawk to quickly remove the other variant before it also sells. I've thought of doing a separate "add framing" product that people can add to their carts as well, however, framing costs can vary a lot and it would get really complicated if even possible. Any ideas on how to neatly contain this under a single product? I have an example of this with variants at the link above.

I appreciate any and all thoughts! 

This is currently only possible with a separate ‘add framing’ product or by using a Squarespace extension called Trunk Inventory. The additional product may be possible to code if you have fixed sizes and frame costs.