$2500 max? WHAT? Sorry to call you out but I find that extremely hard to believe.
You could easily spend 7k , Hell, I have about 7k in my 4800 watt, sealed, climate controlled Co2 grow room. Just buying 4 1000 watt ballasts, hoods, and bulbs will put you at around 2K. plus $500+ for Co2, then you have multiple fans, split AC, reservoirs, water pumps,air pumps, air stones, nutrients, ppm meter, ph meter, etc etc etc. My electric bill is $700 month and I have some of the cheapest power in the country.
At any rate,I wold love to see how you came up with. Maybe there is some hidden cost savings available. But I am likely to chalk it up to not understanding all the expenses of building a grow room. I know that I way underestimated.