Let me put it this way:
If my time is worth $100/hour and I spend 1.0 hours finding (assuming I find one local) and obtaining a used trunk lid, that is $100 and then add in the price of the lid, let's say $200. That's $300. If not local, then (a) add $50 for shipping; and (b) add x days wait for shipping. TOTAL: ~ $300 to $350
- VS -
Taking my car to a nearby body shop (1.0 hrs of my time [most of which is "wait time" which means I can be on my phone or just reading/relaxing as opposed to "work time" for above scenario of searching] = $100/2 = $50) plus paying $75 to $100 for the bodywork. TOTAL $125 to $150.
Finally, with a used one from a different car, the chance exists for either (a) slight color mismatch due to fading; and/or (b) scratches/dings and wow if it was one shipped then that means even more of my time to ship it back and find another one.
There you go, the thought processes of a programmer! Same reason I don't change my own oil or do my own tune-ups. I'd rather spend my free time having sex. :)