You're level 76?! Random loot should include items worth 2k each. You should be able to get 100k worth of stuff by clearing regular dungeons and bandit camps. The hard part at that point is finding a merchant that you can sell to for full value if you haven't invested in the speech perks. Without speech perks, you will usually lose money and clean out a merchant with each item.
Alchemy potions are also very good. Every time you visit an alchemist, buy out the whole inventory (don't bother picking and choosing, just spam the button to buy everything). Turn around and make the max-value potions. Then sell back enough potions to get your money back. You can do the same with soul gems at the magic merchants, but it's more time-consuming.
Try to utilize trainer/merchants, like the Whiterun alchemist and Grelka in Riften (Grelka is especially useful because she is tagged as a general merchant and will buy anything even without speech perks). Train and immediately sell junk to get your money back.
When you're selling your loot, go from specific to general. I.e., start with the smith and sell your armor and weapons, then alchemist and sell potions, mage and sell scrolls and magic robes, and end up with the the general merchant to sell anything left over (again this is irrelevant if you have the speech perks).
Riften is great, especially after you've unlocked all the fences. You have an above-ground ring of about eight merchants, including two generalists (one of whom is a trainer), and five or so below ground, one of whom will buy stolen goods.
Good luck!