My setup without cost restrictions but still being reasonable would be
a 4x4x8 tent $125
2 of HLG triple slate with Rspecs $600
2 Meanwell "b" power supplies, 320watts wach, or 480watts that you will dim
6" exhaust with carbon filter
Oscillating fans
Mostly organic soil grow
When you read about people vegging 1 or 2 plants in a 4x4 its real. Easily 1 can fill a 4x4.