I don’t believe oem is available anymore new. I believe I bought the last one in the US (according to the parts counter guy) from a dealer in Georgia a few years back. You might get lucky though. I would keep checking eBay.
I’ve had mine since May, and I love them. I have them combined with ARB torsion bars, 864 springs, aftermarket bump stops, and TT extended links. It seems to be the perfect recipe for me. I was never expecting a stock Lexus ride, and have been impressed with their ability to eat bumps...
I ordered the wiring harness Ben suggested, but had to cut and modify a bit to fit an aftermarket inverter. I believe this part is for a factory inverter. Also, the harness is small. I had to extend the wires to reach where I wanted to install the inverter.
Not affiliated with these guys whatsoever, but looks like these guys produce some nice products.
https://bigslackoffroad.com/product/land-cruiser-100-3rd-row-cargo-rack-attic/