I stockpile huge amount of SP on my players.

I rarely give players new star since that will ruin their resale value until they come close to the next star again.
Mostly I give SA to players who accumulated enough SP for it when they are 1 point from the next star, often free youth from the academy.

Since SA require 40 or 50 points while new star requires 75, getting SA has better availability if you want to keep your player at the nego list.

Just sold in negotiation a 23y academy youth with CK ability for 4 tokens
I have 3 players sold this way this season, generating some tokens and 400m