Go to a craft store and buy a few bags of colored glass 'stones', like the kind you see in flower vases. For $5 a bag, you've created your own denominations, e.g.:
Amber= 1gp
Green = 10gp
Red = 50gp
White = 100gp
Black = 500gp
Clear/iridescent = 1000gp
etc.
Keep a few spare dice bags handy, or...