As mentioned, the AH will get you a decent assortment of gear.

Heroics will be upgrades as well. In 3.2, heroics will drop Conquest badges, which will get you much better gear then you can buy with badges now. Plus you can downgrade Conquest badges to Valor and Heroism, if you really want something.. for example, say a [Sundial of the Exiled] (84 crit, chance on cast of harmful spell +590 spellpower for 10 seconds).

Depending on your ability to not be frustrated through a ton of deaths at first, PvP is a strong option too. Go with 10 arena games per week, which is almost enough pts to buy one piece. Think of it as 90% of a piece, very cheaply each week. It's something like 12k honor and 360 arena points for a piece (with 344 a week earnt in the arena minimum) or 48.6k honor without arena points. A full set of Deadly gear (one step below the current best arena point only set) from battleground pvp is a decent option to gear with.

You can of course go for both.

Your Naxx runs are going to be nice. Still if you're running with say 4 shammies and a tank or five shammies, that's basically 4x as long as running 1 shammy, since they'll each want the spell damage mace that drops etc.