The only place to buy the KW CULNM1.TG is at led4power.com. The bare leds are out of stock, but he still has 2 reflowed on a 20mm MCPCB, and 4 on a 16mm MCPCB. Not sure when or even if he will get them in stock again.
These are very low voltage leds so even if you want them at 5A you need to regulate the current or they die from overcurrent. For output/voltage information see the OP of this thread: OSRAM CSLNM1.TG & CULNM1.TG 1mm², CSLPM1.TG & CULPM1.TG 2mm² . The KW CULNM1.TG is the last one discussed in the OP, you need some scrolling.