Decimal place error in the pricing. They will honour it, the online system won't even notice.
I'd lay odds that all the big "thousands of items in the catalogue" firms have at least a couple of similar lurking somewhere in the list. When you stop to think creating these catalogues is a major, major undertaking.
As Dennis found you have to watch the handling charge when dealing with CPC Farnell for small quantities. Tends to turn a stonking deal into "meh, average".
As I was reminded the other day when buying an old style printer cable. At £11 it wasn't worth messing around searching t'net to save a couple of £. Especially as it was for a mate, not me, so I'll gte paid.
Even so its rare to see anything that doesn't work out at least reasonable.
As Robert says the trick is to pad out the order up to the free shipping limit, £20 I think.
Lets face it a "Maybe, I might use it, possibly item." is still more for your money than postage charges. Even if it does sit for 20 years before you use it or, as with my last effort, get traded away for something I did need.
Best one I had from them ,was a box of 24 LED bulbs with PIR sensors for less than the price of 3 from everywhere else. I needed 2!
Clive