if you can get only one then get the hps and buy the hps convertion bulb with it. that way you can run your hps bulb for flowering and use the convertion for veg, cuz lets face it switchable are to high priced. you can get the the convertion bulb for a 400w hps for $50 at http://www.discount-hydro.com/lightbulbs.asp


Sunmaster Conversion Bulbs are metal halide bulbs that operate on high pressure sodium ballasts. They are perfect for giving your plants the blue spectrum that they need for the best vegetative growth. These bulbs are available for 1000, 400 and 250 watt high pressure sodium ballasts. The 1000 and 400 watt put out a balanced 4000° K blue light. The 600 watt puts out a cool 6500° K blue light. They are universal burning bulbs which means that they can be used in any fixture, vertical or horizontal. These bulbs are environmentally friendly.