Or almost infinite... You will never run out of spirit unless your dps is very low.
Stone of jordan + legacy stone of jordan,legacy hellcat waistguard, holy beacon, xephirian amulet can all have spirit regen on them. So you will be gaining around 22 spirit per second combined with passives, healing mantra and templar aura.
Basically you just run with 60% move speed with tempest rush, skip all trash and kill elites with seven sided strike and bells. In act2 i get around 2 elite kills per minute and in act3 about 1 per minute.
You don't have to skip trash, they usually die in one bell, but I've found it to be more effective when farming for items.
Buy some cheap vit/resist gear for your templar so you get the 17% bonus to spirit regen.
With higher damage you can drop Healing Mantra for Overawe.
Gear will cost at least 20m to be viable, 50m to be effective. It's a lot of fun if you have the cash for it! I love seeing 1 million damage crits
For weapon, buy a slow 2hander, spear or mace since tempest rush channel cost is based on attack speed. Don't get attack speed on any piece of gear.