I am willing to invest some cash mate for sure, but i also need the right tips not to waste money on useless shit innit
EDIT: info you're looking for: Run that light across the top, throw an exhaust fan at the top corner, intake at the bottom, and a small fan to circulate air around the box.
Really the only thing you need to grow decent smoke is proper air flow, proper lighting, proper temps, and some food for the plants.
For proper air flow, a passive intake and an active exhaust at the top of the cab with a pc fan will work. That handles moving air in and out of the box. Then it's just a matter of blowing a very light breeze on your babies so they develop strong stocky stems.
Next up is proper lighting. In a stealth cab, you can get away with one or two 100w CFL's. They're surprisingly strong in output. If you get a full spectrum bulb you'll be set. Space blankets (2 bucks at Wally World) can be used as a replacement for mylar, or flat white paint (space blanket is cheaper).
For proper temps, this is the tricky part. Stealth grow boxes have heat issues, which is why making sure your exhaust is made. The stronger the exhaust, the less heat in your cab.
Aside from that, there are a few other things you can do to save money on the cheap. In terms of water pH, you can use lemon juice for pH down or baking soda for pH up. Alternatively, you can get a brita water filter (i have a pitcher) and not worry about pH forever. Odor can be controlled with ONA or a custom made carbon air filter (tons of cheap diy setups on the net. Gotta find which one works best for you).
For plant ferts, I don't use any cannabis specific fertilizer (because I'm a cheapskate). Alaskan Fish Emulsion is like 10 bucks and gets the job done. Flowering ferts aren't too expensive either (Dyna-Gro or Alaskan Morbloom for example).
All in all, you can probably build all of this on the cheap. All the extra stuff will go into increasing the quality of your bud or making your stealth box stealthier.
You got this.