What would YOU do if you had $200-300 to build a GrowBox?

Get familiar with Craigslist and the safe areas around where you are (I'm not going to take $300 with me if I'm meeting someone I don't know and they live right down in the city)

I'd buy a used hood/ballast/bulb combo for about $150 (probably 6inch vented with a digital ballast). Next find a used hydrofarm 6inch blower for probably $50-60, or something similar.

I had so much fun building my first cabinet....but it ended up costing far more than a used tent would have cost and it was not nearly as light proof or easy to use.

I'd buy a new bulb before you switch to flower, but if it fires up, the old one might get you through veg. I just picked up 4 90k Lumen Ushio 600w for 54.99 (each) on amazon....usually use digilux, but the ushio was so much cheaper...

Build a big area that you can be comfortable working in. You still have A/C to think about, your dehumidifier, oscillating fans, eventually you'll add CO2, you'll want more light, you'll want a separate veg area.....

A bulb, ballast, hood, and blower will get you started, you'll have to add things to manage your environment. If you build a garden, steel studs are light and can be cut with snips (I know stealth isn't an issue, but do you need everyone to know you are building a room that will contain a few thousand dollars?). From there you can use paneling, panda wrap, both, insulate, etc.

Basically, plan for expansion. Your first harvest should bring in enough for a veg light or some other equipment and you can start expanding slowly. I started with 1 600 for flower/veg and now I have 4 600s two fans, two t5s, and all the goodies that go along with them. Good Luck!

I spent more trying to build my own cab to start just trying to get it light tight. YOu could probably pick up a whole setup with tent from craigslist to start. Focus on the light first and make sure you have the essentials:

1.) A light appropriate to your space
2.) a controllable environment, I like a tent
3.) Proper ventilation/extraction fan (you can skip the carbon scrubber for now
4.) Basic starter nutirents, you can go cheap and when you get a handle of things, add on to that
5.) A PH pen, will help if problems, and a cheap on is only about $10
6.) Soil and containers. I like Roots Organic for my soil.

There will be incidentals, so try to set aside a little scratch fund.

small usb controlable 2lt humidifiers (hot or cold mist) are about $10 on ebay......iv got one and there great.

small usb room ironizers (not the ozone one) are $10 ebay and will clear all the dust particules from the air so the plant can breath in dust free co2 thus non clogging of the stomatas..
the fresh air in your tent/room will smell like a mountain ganja forest air.....it makes sense to me

good luck