Download Minecraft Economy Manager.
Configure the spreadsheet to your liking.
Export your Minecraft Economy Manager spreadsheet to a CSV file.
Copy Minecraft Economy Manager.csv to the folder containing MEM2Ess.jar.
Double click MEM2Ess.jar or run with java -jar MEM2Ess.jar.
*If you don't want names above the items, run with:
java -jar MEM2Ess.jar nocomment
A few seconds later you should have a worth.yml file in that same folder.
Copy that worth.yml file to your servers plugins/Essentials folder and reload Essentials.
Enjoy your servers new well-balanced economy.
*Note: This is not a plugin, this is a standalone tool.
Source on GitHub.

MEM to Essentials 1.1
Convert Minecraft Economy Manager spreadsheet into Essentials worth.yml