They are actually great lights but a little pricey. If you can snag a 20% off digital coupon code, that helps. They send out discount codes all the time if you subscribe to their mailing list.
The 1000 watt, 3 channel fixture with the controller is what caught my eye for a 5x5 bloom area.
The GH series are supposed to be one of the best supplemental greenhouse lights on the market (according to reviews). Gotta buy those in bulk though.
You could build a light cheaper if having large drivers is not a problem (which should not be an issue for small grows).