The answer is really easy, think about it like this:
Do you need the gold?
Do i have enough gold for...
- Repair Bill?
- Flask/Elixirs, food?
- Enchants, Armor kits, belt enhancement?
- Gems?
- Reagents?
- Alt? (New skills, equipment, etc..)
- Cataclysm? (this is an exception)
If you noticed, i wrote the most important as nr 1.
If you don't have enough money for either of the above, i'd say Sell it.(notice exception).
Keep it for your alt otherwise, if it is an upgrade, thats a bonus. It also looks cool, and gives your alt a bit more value.
Hope this made you make up your mind.
I'm out.