I would say definately invest in bigger lights if you can, but that will force u to invest in some ventilation too. Your grow will be just fine without the extra bulbs, but i would say with how low your light is now... you could probably get a 25% better yeild with some better bulbs, but your plants will grow and do just fine with what you have now... As for yeild, i have no clue about your strain, but your yield will NOT be very large with that small amount of light. I would guess anywhere from 4-8 ounces? also depends on if you are going to LST it or crop it? how tall are you going to grow it?
Also, I perosnaly just buy the bulb and a ballast kit from any electrical store. The ballast kits cost me about 70 bucks, and the bulbs about 20-30, then i just make my own ballast, If you have a well set up room with all reflective surfaces, Ive always thought expensive ballasts where a little over rated and can run you up in to the 200-300 dollar range!
as for nutes, I just use nutes from home depot with decent NPKs, I know some people get really technical with it but... idk, probably best for someone else to awnser that question.