I think that the better option is to avoid them. Those wallets are either broken, either empty, so the effort is useless.
Yes, this is just a waste of time.The sellers if they can make money cracking the passwords, they've done it already so there's no use to them to keep those and that's why they're selling it.
So at least, they can earn from it.
This is absolutely true. It is very easy to run a wordlist attack on each wallet. They have of course done that on every one of these. The one they are selling have unbreakable passwords, and even if you have a GPU farm at your disposal it is very doubtful that there even is the advertised private key contained.