This is my first real addon, just made it as a fun project and to solve a frustration of my own. I thought I might share it with everyone here as well
If you've ever had to search through your bags for a grey to destroy so that you can loot an item, this addon is for you - it will show up in those cases and show you which items to delete.
The addon is called Delete Cheapest Item and it's available on Curse:
https://www.curseforge.com/wow/addons/delete-cheapest-item
This is v1.0, so it's pretty basic and could potentially have a bug or two.
Thanks and enjoy!
I just updated it to highlight the items that are cheaper than what you're trying to loot. This should help for now.