U miss out the most important element of all. The tebu

US Prius with dead battery selling less than 2k USD

I saw a few videos on the battery company. They took in a lot of spoil battery, then refurbish them by changing bad cells in it. not sure which part but either end or mid of battery cells will fail first.
The rest is still good for a few years.

Btw China has come out with cells replacement as well, not sure how reliable compared to original ones from Japan

europeans use this method called planned obsolescence and monopoly over their products maintenance. (much like apple dont let ppl repair outside)

even if you know how to replace the battery, there might be certain counters or electronic devices which needed separate tool or programming to reset.
without doing the proper way might cause more error messages.

the mech here sure need to ask germany that side to guide them.

the usual method ppl do outside is they go read their manuals which is compulsory then test it on wrecked car lo.....
if lucky can find free on jewtube.

even repairing VW mechatronics module can get on jewtube also.

8k has 8years warranty from japan
5k has less warranty from china.
definitely take the 8k