Domestic purchase programmes, pursued by several African central banks, allow reserves to be accumulated in local currency rather than by spending scarce foreign exchange. They also give licensed and cooperative producers a legal counterparty at a transparent price, which is the single most effective anti-smuggling instrument available.
The foreign exchange saving is worth stating plainly. A central bank that would otherwise buy bullion on the international market to build reserves spends hard currency to do so. Buying the same gold domestically in shilling terms converts a foreign exchange outflow into a domestic currency transaction, which is a meaningfully different balance-of-payments outcome even before any anti-smuggling benefit is counted.