Amazon for the WRGB90. I bought it in April and works great, 24V 6A Power Adapter AC 100-220V to DC 144W Power Supply US Plug Switching PC Power Cord for LCD Monitor LED Strip Light DVR NVR Security Cameras System CCTV Accessories.
Or aqua rocks colorado website. The guy is on high tech planted tank facebook group, his name is Tommy, ask him first
Be careful some online are fake and are not rated for their actual numbers. I had a pair literally expand and die that I bought as replacements. If you want real ones, I'd order new ones from electronic stores that are used in the DIY communities. What is the voltage and watts the existing one is. You could get away with less at the same voltage too. If I remember some were 144watt 24v. I got some like 120w at 24v ones and they were bright enough.