As a result, I had to source a solution to advertise stock with a finite auction end time. My search led me to 'Sendtric'. They offer a free service for generating countdown timers. You don't need to register or pay for a subscription to use it, either!
The service allows you to define the time zone settings, countdown end date (any date and time within the next 30 days), language, background colour and finally, the text and number colour. They also have a premium solution that provides much more flexibility over the design/fonts.
Here is a snapshot of us creating the countdown timer over at Sentric.
And a screenshot of the final article once we have embedded the HTML code generated...
Our search did unveil some alternatives, so these are also worth a mention too, although we have not personally used them to date: