See, here's the problem we're facing: there are plenty of players and not so many teams to shelter them.
If this is turning into an issue, it's not an user problem to solve, but GLB's.
Overall, this we should increase the value for a team.
I think the first step would be to allow teams to be created on any tier. See, people contested about allowing players to jump seasons as that would cause harm, however, regardless of the tier, there's no team without players, therefore, teams would be created according to demand.
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On a second thought, whenever a human-filled roster (at least 37 players controlled by human users) is not renewed, instead of freeing the team it could go to an auction.
If an user is looking to manage a team, then going after an auction is tempting since he won't have to chase for players on the marketplace or the transfer list. Also, the market dictates the price of the team in an auction, so teams may go more or less than 500 flex, according to its quality according to the user base.
If a team is acquired by a new user, the current roster has the incentive to keep their players, leading to another tier of boosts in the upcoming season.
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On a third note, it is not price that dictates if an user acquires a product or not, on the internet it only matters if it is free or not. Would you pay even $1 to join Facebook? Good for you, 99% of its users wouldn't. I could list plenty of examples on how this business works, but I hope you can Google them (just check the in-app purchase model dominating the mobile applications).
So offering free teams to fill the gaps for the tiers where they're demanded is a great deal, you lose 500 flex, but you make a lot more. Of course, this is the last resort and the free discount would only be valid for the first season. Perhaps the user needs at least 1 player at the desired team's tier to apply for ownership, but this is all food for thought.