MrStinkyanswered grow question 3 years ago I was considering this, then I started a worm bin for castings. The main reason is that unless you are growing big 6 month photo plants is that indoors with autos you just wont have the time to let the worms develop a good level of castings, plus space in the pots would be low due to root formation. In the garden its different - worms have already been composting it for millennia so have their equilibrium established with maximum populations and composting power.
Worms - red wigglers or european nightcrawlers are the best for composting, you can get them in tubs from fishing stores for next to nothing for small scale or you can order bulk weight like 1lb /0.5kg. I am small scale with about 250 worms although thinking of increasing to 400 which is about 1/2lb. I have small daily food waste so cant support a large colony.
You can set up a tiered system for perpetual vermiculture composting for like 20 USD for the materials you need.
After that, if you set it up right and go through the motions you should be looking at a good bucket of worm casting every couple of months. I will probably just add 5% to my substrate in future as I am dry organics. The rest will be going on my house plants, compost teas or maturing to till into next years veg patch.