Like what most have mentioned, if those wallets are indeed true, then the owners would never sell them- I mean 19,400 BTC would equate to around $700 million dollars which would turn any person into a millionaire by seconds. If I were you, avoid dealing with these people and their shenanigans. Most likely like around 99% these kinds of deals would result to a scam.

Again, these kinds of deals should be avoided at once. I highly recommend that you report this website in the forum so that people would be notified at once. There is always that slight possibility that someone would fall into this trap.