Soloing old world instances is a great way to make cash at level 70. I happened to be a big fan of Blackrock Depths, myself. To do this, you need either 280 lockpicking (go rogues!) Or the BRD key. Zone in, unlock the first door to your left. If you are not an enchanter, skip to the next paragraph now. Otherwise, keep going straight, kill the bloodhound, and take a right down the Dark Iron Highway, avoiding patrols. You should be able to avoid aggroing anything simply by virtue of being a level 70 around level 50ish mobs. Head through the gate, across the bridge, and into the hallway filled with fire elementals. You should see Incendius circling the Black Forge. Kill the pair of elementals closest to his platform, then pull him from range. At 70, the only danger to this fight is his knockback attack, so you want to fight him in a position where you will not get tossed into the lava. Kill him, loot, disenchant the brakers, and trace back your steps until you see another locked gate.
Unlock the other locked gate, then unlock the East Garrison Door. Go up the stairs, up the ramp to the spectator section of the Ring of Law, work your way around to the other side, and make a right. You will want to be wall walking for this part, as there are a few groups with very little wiggle room to get around. At the end of the hallway, you should see Pyromancer Loregrain and his 2 adds. There is absolutely nothing noteworthy about this fight, although the adds run at around 20% health, so make sure to finish them off quick. Loregrain always drops a blue that DE's into a small Brilliant Shard, and has a chance to drop the formula for the Fiery Weapon enchant, which usually sells for about 75g on any servers I have played on.
If you are a miner, make sure to mine any Dark Iron nodes that are guarded by manageable packs, the Dark Iron Highway is great for this. Doing just Loregrain will net you on average around 85g per hour, more if the RNG is on your side and you get multiple Fiery drops, less if you do not get any. If you are an enchanter, tack a guaranteed extra 40g per hour on there, assuming Large Brilliant Shards sell for 8g per like they do on my server.
As a miner / enchanter, I have made up to 400g in 40 mins of doing this. That is 10g per minute, certainly not a bad payout for such a low risk run. Your mileage may vary, but I would definitely suggest giving this a shot. If you end up getting your epic flyer a bit quicker because of me, just mail me some Dark Iron Ale … / wink.