Wondering if there's any decent consumables I should be using?

Leveling a new rogue. Currently level 8...

If you're willing to spend some gold, then the Elixir of the Rapid Mind - http://www.wowhead.com/item=128312/elixir-of-the-rapid-mind
Or if you have any Elixir of Ancient Knowledge lying around - http://www.wowhead.com/item=86574/elixir-of-ancient-knowledge

I personally use the rapid mind elixir on all characters I level, between 90-100. It makes those levels a breeze.
Just do all scenarios in Gorgrond so you're ready to finish them (like 1 mob missing or item needing to be looted), drink the elixir and complete all the scenarios while the +300% exp buff is active.
Then proceed down to Talador and do a couple of scenarios there, and you should be 100 before the elixir has expired.

Are they both available on the AH?

Elixir of the Rapid Mind is tradable, so it can be found on AH, yes.
Elixir of Ancient Knowledge is not tradable, but it's account bound.

Elixir of Ancient Knowledge can be farmed here: http://www.wowhead.com/npc=50356/krol-the-blade
And here: http://www.wowhead.com/npc=73666/archiereus-of-flame

Ah shit, the one on the ah is like 50k (which I don't have) and the other is too high for me to farm hahaha.

Ah well, looks like the plan old grind it is.

enchant your weapons. ideally heirlooms but the enchants are only a few hundred gold i believe
elemental force is op as shit