Famously hard to find in stock, the G7 X Mark III can now command second-hand prices higher than its original retail price of $879.99 / £899.99. Canon PowerShot G7 X Mark III | Black | Silver (backordered)2. Why is the Canon G7 X Mark III so expensive second-hand? But the G7 X Mark III isn't alone in benefiting from the renewed interest in older compacts. For now, though, the G7 X Mark III shows that newer doesn't always mean more desirable – especially when it comes to the point-and-shoot revival.