On online auction site eBay, a 100 trillion Zimbabwean dollar note is a collector's item fetching up to $35, a small fortune compared with the 40 US cents on offer from the central bank as it seeks to officially bury the worthless currency.

The unloved Zimbabwean dollar, ravaged by hyperinflation that peaked at 500 billion percent in 2008, ceased to be legal tender on Friday as the southern African country switches fully to the US dollar.

The central bank says citizens have until September to exchange their remaining quadrillions of local dollars for a few greenbacks.

But economists say 90 percent of the economy has been based on the US dollar since 2009, so few people are expected to make a beeline to banks to cash in old notes - especially as they could get a far better deal elsewhere.

On eBay a seller was offering a hundred 50 trillion Zimbabwean dollar notes for $1,000.Zimbabwe's hyperinflation was considered by the International Monetary Fund as the worst for any country not at war.