Why not just get one of these pre assembled for $12 more? To answer the question... I have no idea if the link you posted is worth it but these both have identical diodes and is also using a hlg driver.
Yeah, like pulp said, it's basically a ripoff of an HLG 65. 3x3 = 9 sq ft. If you want to do the laymans method of just using watts, I would aim for around 270-360 watts. Samsung or Bridgelux strips. If you want something pre-built, take a look at the HLG site. A couple QB288 v2s would do well in there.