In order to begin to make a valid price comparison to this used (ie, not new) PC, we'd also need to know how much a used Raspberry Pi system would cost.
The RPi secondary market is a bit nuts; there's minor scarcity at times, plus the fairly strong brand, so people list them at their original MSRP all the time. No idea how many move at that vs. get low-balled.
At some point, dealing with reselling vs. just throwing in a bin (either back-of-the-closet storage or garbage) just doesn't make sense from a time/money perspective.
Go to ebay.com. Search for Raspberry Pi 5 or 4. See actual market prices by filtering to sold listings. Add cost of case, power supply, storage, maybe even active cooler.