Police have charged a couple with "theft by finding" after they forked out a few dollars for a second-hand suitcase at a Melbourne Salvation Army Store that had up to $100,000 hidden in its lining.

The suitcase was donated to the Salvos in Beaconsfield by a woman who did not know her husband had hidden the cash in the bag's lining.

The distraught man contacted the Salvation Army last Tuesday in a bid to retrieve the suitcase but it had already been sold, Salvation Army spokesman Major Brad Halse said.

"He said his family had cleaned out a room and donated some goods. One of the items was a suitcase with a very significant amount of money in it," Major Halse said.

"I guess sometimes people store things of value in unusual places."