The power supplies in PCs are one of the components that wear out. Sometimes the fan goes, because they are mechanical. That's easy, I just replace the fan. But sometimes, it just fails.
They are easy to replace; PCs are like Lego, but with screws. I have a small stock of PSUs (power supply units), so that I don't have to order one each time one fails.
And my small stock has dwindled - time to order more!
So I had a look around, and Bluepoint were offering 15 refurbished PSUs (which means, second hand and wiped over with a cloth) for a mere £1.91 plus Vat. "I'll have some of those" thought I, and ordered 15. "Yes we have them, no they aren't in stock, but we can get them". They took my money, then called back. They don't exist.
So I tried another bunch of PSUs they had, for the same price.
So I tried another PSU that they had on their web site. Not available. So I explained, "look, I tell you what. Rather than me try to guess which of the products that you offer, I can actually buy, suppose you make a list of what you can actually sell to me, and put it on your web site? Because I'm tired of playing "Guess the product" with you."
And I went to eBay.
Where I found some excellent, brand-new, 700 watt power supplies for only £5 each, free postage. So I bought ten.
A few days later, I got a message frmo eBay. Someone had been very naughty, and the items didn't exist, sale cancelled. I went to Paypal, where I found that the £50 had not been claimed, so I cancelled the payment.
Which took me back to square one.
So I went on a rampage on eBay, and bought every PSU that was the right kind and was under £7, which means I now have 13 assorted second-hand PSUs on their way to me.