If you're looking to purchase a second-hand property through reliable and legal means, you can never go wrong with Subastas del BOE. 

Auctions, both judicial and notarial, are carried out through the BOE portal. All auctioned properties have been subjected to proceedings conducted by the General Administration of the State and the auxiliary to the Administration of Justice. This is to ensure that all items are acquired through legal means. 

The auctioned items are seized and confiscated from criminal activities and acquired by the state through judicial agreement. 

How to place a bid?

If you want to bid for a property, first, you must create an account on the portal with your verified information. Next, go to the "Bid" tab to check the available properties for bidding. From there, you can select your preferred item. If no minimum bid amount has been set by the Auction Management Authority, you can bid for any value. Otherwise, the system will offer a drop-down with the first 100 possible bids.