Svelte rather than tiny bars for the kids, I suggest American gold eagles. They come in .1, .25, and .5 ounces, so as low as about $220. It is legal to make fake gold bars, though obviously not sell them as real. But even making a fake American coin is a serious federal offense that the FBI and Secret Service will both come down on. That makes coins lower risk than bars. Bars IMO have no offsetting benefits.

Another option would be $5 gold commemorative coins. The plus side of them is they mostly have a smaller markup over melt value from secondary markets, have designs that change every year, and cost about $490 from reputable online sellers. The down side is they don’t have a nice round amount of gold. They use the ancient formula from when the US was on the gold standard, so have something like .241oz.

California charges sales tax on gold and silver for purchases below $1500. So it would be a bit crazy to buy less.