Lighting Question, is it worth it?

[Volker]

Ok I found a website that sells a sun system 4 150 watt HPS light for like $100 brand new with a 5 year warranty

Is this 4 x 150W HPS for a total of 600W? Hope ya have good ventilation! I'm guessing you meant "for", and it's a single 150W HPS

Tough call. I'd use the HPS with your current CFLs as sidelights, giving you about 225W of mixed lighting. Your flowering box is the same size as the inside of my closet (I'm using 300W of CFL): you should be able to do 2 or 3 plants in that size easilly with those lights, depending on strain, and assuming all other needs are met.

As far as vegging on the shelf below, there's no easy way to lightproof between shelves in a closet or wardrobe. You're prolly better off with a seperate veg area; during bud cycle absolute dark is important.