Alternatives to the coins supplied in Puerto Rico
Board Game Bits has little wooden disks in various sizes.  You could get some cheap plastic pirate coins you can get at pirate stores.  This might help spice things up also.  There is also a company out of Australia, Campaign Coins, that specializes in coinage useful for games and LARPs.  They're prices are a little steep at $7 for ten coins, but they have a good selection of different designs.