Steve Walker wrote

Tenuously on-topic, but hopefully someone can help.

I use an external 5v/12v power supply to temporarily run hard drives
during repair and tinkering. The Chinese rubbish they sell on eBay (eg
141793905523) has the quality & durability of a Kinder Egg toy. I've had
about 5 of them now, they always fail.

I've had a couple fail, and a couple more that haven't in years.

I would happily pay £20 for a good quality version from a reliable
manufacturer. Does anyone happen to know where something like this is
available?

Fraid not. Tho the better brands from the US etc are more likely to survive.