n previous versions I used this command to verify the value I set up to buy tickets, however, this command does not exist, which one should I use?
This was an option of the old, removed ticket buyer. It was replaced with a new ticket buyer implementation which is configured using flags or config settings. There is no way to query or modify the new ticket buyer from the JSON-RPC interface. It can be done from the gRPC interface, but dcrctl does not use that RPC server and we don't have any other command line clients for the gRPC server.
Another doubt, Is this command correct for tickets at 70 DCR? ./dcrwallet -u USER -P PASS --walletpass PASS --enablevoting --enableticketbuyer --ticketbuyer.balancetomaintainabsolute=0 --ticketbuyer.maxpriceabsolute=70