I've always been a large fan of Ancient Egypt, ever since my childhood. As it was another major factor that contributed to my getting involved with roleplaying. I used to have "adventures" in my daydreams as a kid of being there. *Memories*
What if the sources of precious metal in the realm all failed, so that the only sources for gold and other precious metal were hostile foreign lands? Gold coinage might become increasingly rare, resulting in hoarding. Player characters that appear with masses of treasure might be suspected of being in the pay of foreign powers.