Cheap soil help

Hello this is my first ever grow. my friend has his medical card but cant grow where he is so im his caregiver. This initial grow is mostly for experiance so i am going cheap and will then upgrade my equipment. Grow info, ive built a 2ft x 2ft box 3ft high. Will be using 8-26watt cfl's. General hydro florabloom gro and micro nutes. Im growing 2 autoflower nothern light plants.

My question is im just using plain cheap potting soil as ive heard you dont want mg with time released nutes. Is there anything cheap i should add to the soil to help. Key word cheap. Or will it be ok by itself until i start with the nutes. Im starting from seed.

Thanks in advance for any helpful advice.

you want a really airy mix of soil adding perlite or similar will aid with drainage and oxygen to the roots. go steady with nutes untill the babys have a good rootball and are growing nicely

Time release MG potting soil is fine if you're growing on the cheap.
If you wanna go organic you can use MG Organic Choice and add some composted chicken litter. It's like $5 for a two pound bag. It's called ZOOM! and they sell it at Lowe's (they don't sell it at Home Depot).
Get yourself a bag of MG seedling starter to be safe. It's like $3. Or you can use the plain MG Organic...it's the same stuff.

I add perlite , hydrated dolomatic lime an composted manure to my MG soil.
Organic indoor, moisture control outdoor.

peat, perlite, and a bag of manure. feed with compost tea. i like rabbit or chicken poop. cheapest and most taste-producing mix on the market....lol.

Wow thanks for the quick replys guys.