Thank you both for the advice. I was wondering, is there anything in RFC that can be sold on the AH, like blues? Maybe I am just not looking right but sometimes I see things on the AH that were bind on pickup for me.
Most bosses will drop blues, but almost every boss drop is BoP and thus cannot be sold on the AH. Killing everything in a dungeon can nab you a bunch of green (and rarely, blue) items, as well as cloth and vendor trash. That's where you would make money.
Oh, and if you have Enchanting as a profession you can disenchant the boss drops and sell the shards that you get.
But realistically speaking, you'll make more by questing or running dungeons at 60 than you would by running level 15 instances for drops.
I really like soloing content. On my first character (back in 2005 or early 2006) I soloed the Deadmines at level 30. It took me almost 2 and a half hours, primarily because I had terrible gear, no idea how to spec, and wasn't that great at the game yet. But I had a blast, and it was a TON of fun. As said, since then I've soloed a ton. The achievements are the primary reason, but I also soloed Stratholme dozens of times to get Deathcharger's Reins
(back when they were a 1/10,000 drop rate). I ended up making several thousand gold off of rare drops, Runecloth, and the shards I disenchanted from boss items. This was in TBC however, when such items were in more demand.
Nowadays I primarily solo raids like MC, AQ40, Karazhan, BT, and trash in ICC for mounts and reputation. You can still make a pretty penny off those raids; Sulfuon Ingots and Blood of the Mountain sell for a few hundred gold each on my server, making MC a quick, painless, and somewhat profitable venture at 90. But again, at 60 you'll be a bit limited in terms of profit and what you can survive.
Best advice: try it out, see how it goes! I constantly try to push myself by soloing things; it's my primary reason to get better gear!