Find the happy medium...
I am sitting on a pile of old gear thats costed a small fortune over the years, because I didn't just get the good stuff at the start.
Lights/fixtures is a huge thing. Save and buy the end game first. Saves hundreds. (Currently, I'd suggest them nice little 315w CMH sets, they run cooler than MH/HPS, and with better light for the wattage.)
Nutes, medium, fans, all that, spare the expenses, go generic, its all the same in the end. Even bulbs for the most part... you can go all out on some Ushio or Horti-Eye's, but... iPower scores damn near as high in light tests, fr $20 a bulb.
Certainly do not attempt to flip to flower until you are ready to finish. Don't give the plant the chance to get beyond your rooms abilities.