No large retail business is ever going to sell items at a loss, they aim always to be in profit.
If anyone takes a hit it will be the manufacturer or the supply chain.
What I have read, is marking down is bad because it reveals the true cost, luxury goods have to have a high price or they are no longer luxury items, most stores buy goods for sales (they are of lower quality or spec).
Price has little to do with value but what customers will pay determines price.
All the computers I have ever owned have been used, some 'refurbished' from memory the highest I have ever paid was around £70. They all worked until the operating system was no longer supported or I tried a modification too far.😒
My first, a Tandy TRS80, had been returned, it didn't power up, I overheard it being returned.
I asked the shop manager if it would be repaired, he said no it would cost more than it was worth.
But the box contained the TRS80 computer, CRT Monitor, Cassette Recorder.
In the end I paid, £20 for it, the PCB had cracked across one corner breaking the power circuit, a soldered bridge over the crack, and some epoxy job done. Tandy Basic here I come!