I've heard good things about the black boxes on ebay. Just be warned that when you buy those the warranties can be non existent or very very difficult to deal with. You will also need to buy 2 LED fixtures for a 4 foot tank.
Go on to Amazon and get either the
GalaxyHydro 165w 55x3w or the Hobbie Bug euphotica dimmable. They are basically the same things and are both really good. I think they both come with a hanging kit but the Hobbie bug definitely does.
I have the hobbie bug over a 10g nano on 50% actinic and 50% daylight.
Yeah I got 1 light off of Amazon for on my 30 gallon tank and that's the new ocean revive t247 and it's a very nice light and I got it at 50% blue and 50% white channel
At that price your only LED choice is one of the Chinese from either Ebay or Amazon. I have run 1 for the last 2 years on my smaller tank and all my coral (including SPS) is growing like gang busters. I am now in the process of taking my T5's off my 125g and adding Chinese LED's to it. They start about $85 for the basic model and go up from there depending on how much controllablity you want. The ones I purchased have the ability to set a ramping program via your Phone/Ipad and they ran about $140. Figure out your budget and what is important to your. FYI: most of the lower costing ones are made in the same plant and the retailer just slaps their sticker on them. The higher end Chinese LED suppliers put their custom LED configurations in them and have different control options but it my understand they are made in the same plant. One of the reasons I went with the Amazon lights the second time around was A) I was dealing through Amazon and if I had any issues I would let Amazon deal with the manufacturer and B) The look identical (inside and out) to the ones I purchased 2 years ago but had just a different sticker, but were $100 cheaper then what I paid previously(the original supplier no longer sells this model). If you are not comfortable with the Ebay/Amazon then look at Reef Breeders, Reef Radiance, and SB Reef Lights. They are a little more $ but still much cheaper the high end lights.