Yeah Home Depot should sell promix and sunshine mix soils. Just buy one of those and a bag of perlite. Whatever you do, do NOT use outdoor soil indoors unless you sterilize it first by baking it in the oven at 350 for 30min. I know so many people that just started their plants using outdoor soil, then transplanted them to a good soil mix, and every time they have bug problems.
I have never, ever had bugs in any soil Ive bought from Home Depot or and local hardware store, yet when a friend donated 3 Diesel Ryder autoflowering plants (2 female 1 male) to me a few weeks ago that had been planted in outdoor soil they had gnats allover them. I have treated a few times and have fly strips hanging up but now all 19 of my plants have gnats in the soil, YAY! At least its not spider mites or something that actually eats the foliage, but gnats still eat the nutrients in the soil & their larvae eat the roots so I still need to get rid of them.
Just get something without nutes and avoid the word organic, it basically means that the soil will be more acidic than cannabis prefers. Make sure to mix it with perlite then just add nutes to your water. For veg, use Alaska Fish Fertilizer (5-1-1) and Superthrive, both can be found at walmart.
KB