Unless you moved into a house with a grow room already there, spending $100 and putting plants under a light does not mean you have a grow room.
On my first real grow I spent about $1200, that included:
2 600 watt lights w/hood
6 in cabon filter
6 in exhaust fan
6.5ftx6.5ft grow tent
30ft of ventilation ducting
r/o filter w/reservoir and watering wand setup
A nice mister for foliar feeding
soil, pots, nutes and stuff for compost tea, air pump for tea brewing, 12x clones
I think that was everything. When I was younger I put some plants in a closet with a light, but that is not really a "grow room".
I could have shaved maybe a little off my total if I had shopped around a little more, or looked for sales, but for the setup I got, for the money I spent, it would be hard to do much better.
After all my first grow with that setup yielded 2.4 pounds of VERY nice GDP.
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On the left, the described grow room in week 5 of flowering, I think the cola close-up was taken about the same time.