I built my own stand and sump. I wanted the sump to maximize the interior space so that was the only way to go. It still cost me almost $400, the actual sump glass was about $300 but I went back and ordered the glass for the baffles and partitions and did not ask the price. To my surprise it was $100 for a minimum order. I was ****ed but what could I do.
It is a good idea to convert the metric to inches for the plumbing.
I am using a Reefbreeders Photon V2 and so far I am very satisfied. I also have one of their lights for the refugium. Kind of a knockoff Kessil H380. For my main pump I use a Jebao DC pump, it works fine but the who knows what the long term reliability will be. For powerheads I use a pair of Tunze 6095's. My skimmer is a RO 150-INT. I also have canisters for carbon and GFO, but only run carbon at the moment.
So many choices but so far I would not change anything. It has only been a couple of months with this tank so time will tell.