The new £1 coin has been placed for sale online by sellers asking several times its face value.
The new 12-sided £1 coin started to enter circulation on Wednesday - and bags stuffed with the new coins have been delivered to banks up and down the country.
New £1 coins have been placed for sale on eBay, with some sellers wanting £10-plus and others asking three-figure sums for particular coins.
The new £1 coin could also prompt an upswing of fundraising drives by charities as people look to dispose of their old round pounds.
The legal status of the old round £1 coin will be withdrawn on October 15.
From this date, shops will no longer accept the old coins and people are being encouraged to use the old coins they are keeping stored at home, by spending or banking them, before then.
The National Council for Voluntary Organisations (NCVO) said in a blog on its website that there are likely to be "fundraising opportunities for charities both around the launch of the new coin and across the transition period".
The website says: "Some of the most significant fundraising opportunities are likely to be after the launch and over the summer, as members of the public become aware of the withdrawal of the old coins and start to think about how to get value from them."
The Royal Mint in Llantrisant, South Wales, has been making millions of the new £1 coins per day in the run-up to the launch.
The new coin has been described as the most secure in the world and boasts high-tech features, including a hologram.
They have a gold-coloured outer ring and a silver-coloured inner ring and are based on the design of the old 12-sided threepenny bit, which went out of circulation in 1971.
But consumers craving a snack or trying to park may face confusion when they attempt to pay at vending and ticket machines, as some do not currently accept the new coin.
Tesco trolleys across many of its stores were being unlocked as the supermarket giant performs upgrades so that they can accept the new coin.
A Tesco spokesman said last week that "fewer than 200" of its stores are affected.
The Automatic Vending Association (AVA) estimates around 85% of vending machines are currently able to accept the new £1 coin and all will still accept the old coins.
It said that with around half a million vending machines across the UK, ensuring all of them are upgraded is a "major operation".
The body has estimated that all vending machines will be fully upgraded by the end of the transition period on October 15.
One pound coins were first launched on April 21 1983 to replace £1 notes. The Royal Mint has produced more than two billion round pound coins since that time.
The production of the new coins follows concerns about round pounds being vulnerable to sophisticated counterfeiters.
Around one in every 30 £1 coins in people's change in recent years has been fake.