The trouble that I ran into when I run both CFL and HPS are leaf tip burn.

As my grow got bigger, the CFL's gave way to the MH and HPS. For obvious reasons.

Then, to keep the CFL effective, I had to get them real close to the sides of the plants. Leave tips were / are constantly getting too close to the lights and I sustained some leaf tip damage widespread.

Add the fan factor and the fan will blow the leaves up against the floros.

The floros are great if that can be controlled.

The 150W HPS will be fine for growing two small to medium plants if the grow area is small enough.

Your space is, as your post indicated, 8 sq. ft.

That is a lot of space to light up for a 150W HPS. Even if you are growing only 2 plants, the light will dissipate over a greater region.

My grow box is only 3.75 sq. ft. but, it is enclosed, very tight and compact...thus the light doesnt have to cover anything but the canopy and the rest is reflected back onto the plants.

If you are gonna use 8 sq. dont go with less than a 250W HPS.

But you need an MH. Home Depot sells them too. HPS will tend to stretch plants more than desired. It beats a regular light bulb, but for vegging, I would take CFL anyday over an HPS.

The most popular thing going these days is a dual unit...

You can veg with MH, then, with a flick of a switch, flower with an HPS.

All your problems can be solved by buying this: http://discounthydro.com/superspectrum.asp

Again, I do not believe a 150W HPS light will coax the true potential out of 2 plants over an 8 sq. area.

Yes, you can grow weed, but they wont be what they could be.

Get at least a 250W and get either CFL or MH for vegging. Get a 250W HPS for flowering.

Also, a do it yourself ballast is called a MOGUL BASE.

The only drawback with those, is that when you build it yourself, now you have to deal with light reflectors and stuff....other wise the bulbs just hang down. THat is fine too but then you will need more than one bulb.

Gets a bit confusing with all the options when your budget is tight.

Mine isnt so I got some of EVERYTHING and found what worked BEST.

Take your pic...but remember, the plants WILL grow. Your lighting needs will evolve as well. Think about 60 days into growth and your light needs will change as well.

If you go with 250W MH to start, you will be fine. Then flower with the HPS.

Hope this helps.