200 Soviet nukes lost in Ukraine -- article from Sept 13, 2002. There have been reported losses of nuclear submarines at sea since then as well (though those are improbably recoverable).

A Pravda article about an accounting glitch is not terribly convincing. Accounting problems do not even mean that the bombs were accessible at any point (assuming they existed), much less that they have been available 'on the "black market" (thanks to sloppy soviet handling practices) for decades'! Srsly.

(Nor do lost submarines count; the US and Russia have difficulties in recovering them, black-market groups are right out, even the drug cartels can barely build working shallow subs.)