Farns
Im not sure whether that 17W LED would give you enough output, and for the price you could probably get more watts/money elsewhere. The LED DIY project would be a fun experience (especially if you don't solder much) but again is a larger investment on something that you don't have a "guarantee" it works. If you get an HPS bulb and ballast combo that doesn't light up, the company will likely just replace them for you, but with a DIY project there is so much potential for user-side error introduced that you'll now have to troubleshoot, identify the faulty component, and possibly order a replacement part.
Personally, I have my BA in Elec. Engineering so I try to go as DIY as possible - fans, lights, carbon filter. I usually start from whatever old power adapter I can find and prototype a board to give me whatever function I'd like.( old laptop adapters or old console power blocks usually provide sufficient voltage at a high current ). It is really fun, but takes up more time than you would think - I can definitely see the up side to a "plug and grow" system if you really don't care much for getting your hands dirty, or if you don't have extra time and just want to grow.