There are three fundamental decisions you must make in setting up a small
indoors grow.
Grow space
Light
Grow Medium
I assume you have already chosen your grow space?
In an MJ closet everything is centered around the light. The size of the closet and the cooling system that you use and your budget. will limit the size of the light.
A 400W MH will cover a 3'x'3 canopy giving about 200g of bud every harvest, even a lot more in the hands of a skill full grower. A unit like that can be bought for about $150 - $250.
The other big decision is the grow medium. Soil, coco coir or one of the several varieties of hydro.
Like the others said above, to give you useful advice we need to know something about your budget, your grow space and your choice of grow medium. It would also help some to know what is the minimum you need in terms of yield, i.e. 1oz per month 1oz per week ...
Apart from the choice of light, the stuff in RollMeOne's list is pretty standard to all grows, but there are quite a few more items and many of them depend on your choices above.