You can also use a logout for the full 160 turns before you buyout your private. Private market units generate at:

Troops=(Starting Private troops×(0.985^Turns you are logged out)+(3×Land×Turns you are logged out)

For turrets and jets the 3 in that formula becomes 2.5 and for tanks it is 1. A 40 hour logout is particularly effective on Team because the max Turns of 160 is higher than other servers. You can bump your private market to around 2.35x it's normal size that way on this server.