Makes me glad that I specified a zero-value order safeguard on our website; when a glitch caused 3 items of £500-£700 to be zero priced it was not possible to continue through checkout, as all delivery zones have a minimum value of £0.01 to qualify.
Of course, if the glitch had priced them at £1 or 1p, then no doubt there would have been a lot of orders
That said, one person did discover a convoluted workaround to get free items using a web form only available to people with a trade discount account. Of course, although it was a contract that we inadvertently accepted by delivering the items, the terms of the account were that it can be closed at our discretion, so his business now pays full retail if they want any parts from us. Was it worth a free pair of boots? Probably not in the long run...