Is there a reason that MegaCrop is not being considered? For cheap, reliable, and simple, it would be pretty hard to match.
Also, if you are doing coco, I would be pretty careful about assuming that you do not need a ph meter. Coco is a hydroponic medium, it does not help out with ph or nutes, it is all up to you. If you end up with a problem, getting it sorted will be difficult if you do not have a ph meter in hand. Ordering one once you have a problem may be a bit late.