Items: What to keep!? What to sell!?
WK mentioned he was paranoid about what to keep and what not to, and rightfully so. I figured I'd make a thread. Others, feel free to contribute if I'm missing anything!
This post will focus primarily on TREASURE items. There is no real need to sell any other item types in this game as they are all useful and/or not very profitable at all. You can get rid of the excessive amounts of Bronze Bangles or whatever though.
If it says "Debased" or "Coin" then keep it. These are extremely useful for postgame leveling (which you'll want to do if you want to challenge the tougher enemies in the game). You can do the push to L99 before the final boss fight but honestly it's not required.
You need one (just one) of each of the following for the various weapon upgrades
Rusted Bit
Glass Gemstone
Sturdy Helixhorn
Metal Scrap
Coeurl Whiskers
Cactuar Needle
Dynamo
Sky Gemstone
Hydraulic Cylinder
Magnetron
Magitek Core
Monster Claw
Barbed Scythe
Earth Gemstone
Spiked Armor
These are required for car upgrades
Supercharger
Turbocharger
Aero Wax
Airflow Compensator
Auxiliary Tank
Magitek Generator
Fiberglass Coating
Reinforced Fiberglass Coating
Superhydrophobic Coating
Enhanced Headlights
It's also worth keeping a Repair Kit on you at all times. I just bought 20 and left them to sit in stock forever in case I stumble across one of the many broken down cars in the game. Likewise, always have at least one potion on you at all times. That's a bit easier but if you do run down to 0 and think "it's cool I have hi-potions", get a few potions anyway because they are actually required for certain quests.
All the other treasure items are essentially only for elemancy purposes. If your'e into elemancy, you may just want to not sell anything at all. Personally, I rarely bothered with it. Explaining which each of the elemancy effects each treasure item has would be incredibly time consuming as there are a lot, so just note that if you are wanting to do dualcasts or limit break casts or whatever, you may just want to hold onto everything. I really don't feel it's needed in FFXV though.
