Used: Custom Ryzen 5 3600/16GB DDR4/1TB SSD/2060 6GB/W10/B at £400 Instore @ CeX Newton Abbot

When buying this type of gear second-hand, how much cheaper should used gear be vs new? I'd say the saving should be 60% or better.

If new, the CPU is 70, RAM 30, SSD 45, a better GPU (5700- and this could be ex-mining) 150, case 25, MB 50, PSU 50. Windows keys cost almost nothing. A second hand PC should only be considered if it represents a massive saving over a new build unless it has extraordinary circumstances (someone you know bought it, and has to get rid of it almost immediately down to financial troubles, say) and you have first hand awareness of its provenance.

It gets worse- if this was a shop build, PSU and other components will be rock bottom. And the punter may be dumping it for reliability reasons that may only show up across continuous use (ie., it will turn on and seem to work fine, but have mysterious issues across longer use).

Despite the savings I can’t trust CEX, a lot of their PC gear has been shagged out mining hardware. I’ve got lucky a few times in the past but I usually do whatever I can to avoid them.

I know this is expired but avoid buying a pc from cex if you're getting it delivered. They'll have you waiting a whole week before telling you it's already been sold if it's a really good deal, I bought a couple 2060 builds for like 350-400 that never turned up. Did it to me 3 times over the Xmas period