This domain name hold a great value, it will be categorized with SIDECHAIN projects ... it's for this they are priced at that amounts.
Side chain projects are usually used to create a new chain that support the main one in the goal to prevent surcharging it (To scale it in other words) ... but since ethereum are upgrading to ETH2.0, they will solve many of problems including this one and will be operating on POS consensus mechanism.
But it can also stand for other usage purposes "accompaniment" of the main project.
Low XX,XXX/Mid XX,XXX
optimum circumstances: High XX,XXX