I haven't bought any lost wallet.dat files nor have any plans to do so. However, I know that there is no way you can get funds from those wallets. Whoever is selling these wallet files, are just scamming people.
For common sense, think that why would anyone sell these wallet files if people could retrieve the money from them themselves? Why not they get that money in those wallets
The answer is simply that they can't extract the money but they want to make money from us by fooling us.
Just stay away from these so called getting quick rich methods, you will only end up losing your funds.