Changing Form Item Price Using Checkbox

I run keychain fundraisers through my website for local organizations. Most of the keychains purchased through the fundraiser are local, but some may have family/friends elsewhere that would need the keychain shipped which I’ll do for the organization.

My problem that I’m trying to overcome is, the purchase is through a Wix Form, which seems to only allow for one item price. How would I use a checkbox for shipping to change the price of the keychain from $10 (base) to $15 to include shipping?

This is apart from my storefront, since all information needs to be put into a dataset separately from my normal products as there is a lot of different information that is going to be passed around beteen fundraiser organizers and myself, and the personalized keychains going to those supporting the fundraiser. Hence why I am using a form for this instead of the storefront.