Engelhard Australia bullion is very popular with collectors but very difficult to find in North America.
The 5 oz that sold for $386 on Ebay was one such bar.
Engelhard bars are no longer produced. That helps with popularity. They were also produced over many years in many styles. Most types have unique serial numbers. That helps with collectability.
Odd sized older poured bars are quite scarce and are attracing more specialist collectors. Think...
Your ability to add gold and silver depends less upon debt and more upon net worth and cash flow.
Having no debt means little if your cash flow just barely covers expenses. I have a home mortgage and car payment but still have plenty to purchase metals. With sufficient cash flow you can add...