Find the 1 or 2 things that each person on your team wants to do in 2-3 years, and find a way to give it to them. Follow up with weekly 1 on 1 meetings, where they control 70% of the agenda.
This is free.
This is free.
I don't know if weekly 1 on 1 meetings will be effective, cause in practice I will need to fit my time to "fight" for this goals and show progress; maybe troubling my sprint schedules and projects releases..
But, that's a try :) Thanks!