Multiplayer is broken. I know how to fix it, but it would take a bit of work and this was only meant to be a 48hr mod. Open source, use how you wish.
After a long time 'hoping' that someone would make a proper economy/shop mod that doesn't require a server, I decided to just make one myself.
Introducing Offline Economy!
This mod adds just one thing; the Market block.

The Market block is a simple block that is crafted using 8 wood plans in a chest pattern, with an emerald in the middle:
The Market is a simple block that takes 30 random items each morning and offers them for sale.
You can set what items will be sold, along with their buy and sell values in the config file.



I do have plans for this mod, and I will be updating it over time. If you come across any issues, or if you have any suggestions please leave them below! :D
There are some commands, but I'm too lazy to look them up right now.
This mod is heavily inspired by ProjectE, but I never liked how things transferred 1:1. I prefer the idea of buying items at a markup, and selling at a loss.
I also didn't want to put every item in the player's hand, but also didn't want to go the ProjectE route of having to discover the items first.
The compromise is that you only have access to 30 random items.
I plan on adding different Markets with different themes, such as a food stall or tool shop.. but those will come later.
Source: GitHub