This reminds me of the Kobold/Skullclamp Tendrils decks that were played awhile back, though you need ways to kill permanents to generate your storm. From the looks of it you're going the budget route, so things like Moxes and Lotus are out. Also going to leave out the Kobold/Clamp engine because at that rate why not just Tendrils them out?

You should look at Black/Green because not only does it have several creatures and spells which are incredibly cheap but they also have quality sacrifice effects. Green has several that are cheap and toolboxish enough to either speed your deck up or slow your opponent down in order to buy yourself more time. I'll try to avoid listing ones you've already mentioned.

Crop Rotation
Krosan Wayfarer
Metamorphosis
Sakura Tribe Elder
Spore Frog
Tinder Wall
Harrow

With Crop Rotation and Krosan Wayfarer being the two real gems there. Wayfarer gives you plays like fetch Forest, Wayfarer, sac Wayfarer to play Forest (or best case scenario another fetchland), Crop Rotation to fetchland, sac for Bayou, Ritual, Ordeal for 5-6. That's doable with nothing real fancy and only 6 cards. In fact this type of deck would want to run as many fetchlands as possible just to contribute to the overall Gravestorming.

Black of course has tons of cheap sacrifice effects.

Bile Urchin
Blood Pet
Burnt Offering
Cabal Therapy
Crypt Creeper
Culling The Weak
Diabolic Intent
Dredge
Innocent Blood
Living End
Rain of Filth
Sacrfice
Skulltap
Tendrils of Despair

Green also gives you quality sideboard options for dealing with enchantments/artifacts and the like as well as general brokenness such as Regrowth and ESG.