Rather than a perk economy, could squad members just shuffle perks between themselves? Or perhaps have some sort of squadron perk bank, to be distributed as the CO sees fit, squad members can deposit as they wish. Just some way of donating perks, no 'profit' or benefit for the perk giver needed. There have been numerous occasions where I have wanted to roll a 262 with someone or vice versa and the other was lacking the perks, I'd have no qualms just giving them the difference. I think a lot of people would do the same.
Instead of a "squadron perk bank," perhaps the Missions option could be used to allow a perk-rich player to help a perk-poor player.
Two players join a mission with perk planes. As long as one player has enough perks to cover the bill, they both can take off.
If the perk-poor player gets shot down, the donator loses the perks.
This would prevent trading and eliminate the need for a "squadron perk bank" but would allow a perk-poor player to fly with friends.
best