I would not say it is hard. Just that it is tedious.
That link. Could go either way from where I sit. If they are legit then most likely they did b) above*, sold off all the buttons, screens, slots, motherboards and whatnot separately, and looking at the rest of their listings they are doing just that (that and the fuses for things likely being them buying in a reel, the picture there displays some cut tape from one, for fractions of a cent each and slicing them up to send out to mark up many more times -- the claim they are a student so likely someone in the electrical engineering persuasion as tend to be the ones to play such games/figure such things out).
*if you have the time and funds to sit on things then something is often worth more as parts than it is as a whole. Sentimentality and lack of funds lead people to pay inflated prices to fix things.