Offering travellers the option to “bid” on an upgrade to business class isn’t a new concept. Several airlines have been running their own auctions for upgrades for some time. It looks like Aegean has either started offering this upgrade option or is simply highlighting it more.
Either way they’ve outlined how the upgrade auction system works and it’s not complicated.
I’ve used this kind of system in the past with another Star Alliance member airline South African Airways.
One thing to note, however, is that your highest bid is the actual bid amount that you’ll end up paying if you win. It’s not like bidding on eBay, for example, where your winning bid simply beats the runner up.