Look good to me on the price and I’m using the 312 boards from them right now. Considering these are Samsung chips that are not made in the USA , I’m ok buying them cheaper. Considering hlg only stocks the flagship model for a ridiculously expensive price, makes sense for them not to sell...
Sheet of aluminum is about $75
https://www.midweststeelsupply.com/store/6061aluminumplate
Driver is $180
https://power.sager.com/hlg-600h-54b-3991246.html?utm_source=googlemerchant&utm_medium=click&utm_campaign=power-brand&gclid=EAIaIQobChMI_b-M-sz12AIVB1p-Ch2PQw3JEAQYAiABEgLrI_D_BwE
4 boards...