The guy on Ebay is the only one I can think of. NOS are hard to find too. I bought a NOS HJ lighting harness plus a HZ GTS/Sandman light harness 6 months ago for possible future use, but they were "off-Ebay" purchases from a friend who got hold of some old dealer stock. They were around $200 a piece. I also found a NOS HK GTS under dash harness a while back and it was around $500.

I'd just go looking at wrecking yards and get some good secondhand harnesses and re-do them yourself. The engine harness for the HJ Sandman is the same as any other HJ V8 (apart from the very last HJ's with ADR27A). The headlight harness are the same as any HJ Holden/Belmont or Kingswood except 1-tonners. Greg at Classicozwreck may have some. I don't think there are any HJ's in the yard with a good harness but he may have them inside.