I have travelled domestically with bullion -- no problems, but please be aware that the US domestic airport security agents (TSA) immediately identified the "objects" and wanted to touch them. It is not illegal to travel domestically with bullion even greater than $10,000 value, but internationally that must be declared.

Also be aware of certain policing organizations that confiscate bearer assets (cash, bullion, certain old bonds) because they perceive those assets as possibly drug-trade related.