I'd need an app for iOS or Android that would be able to allow a user to write down a list of things they need, relate that list to a site which could be used by other users to fulfill the specific need.
one bottle of water
one bag of chips
Let's say there's a Tesco integration in place.
User B could click on A's list and if they want to buy something for A, they would click on the item and be taken straight to the integrated site.
We can estimate the effort together once we settle on the requirements. Initial thought: 80 hours for a first version.
If agreed upon, ongoing work would be required once the project is live.