About 20 years ago I was very close to buying a tank. The cheap route would have been a Polish surplus T-55 and the nice route would have been a swiss surplus Centurion Mk III or Chieftain. The centurion was the far better vehicle, and nobody takes better care of surplus vehicles than the swiss. The RAC museum at Camp Bovington in the UK was going to make the arrangements and they do that all the time for private buyers.
The reality of owning a 30+ ton tank is they are actually fairly fragile, need many hours of maintenance compared to running hours, and in many cases you need another of them to recover it if/when it breaks down. The cranes, tools, etc are expensive along with spare parts. While I could have made the cost of buying one work, the "other costs" talked me out of it.