I saw a player I sold off of my utopia team two seasons ago and I can't place a bid on him. I see this message instead,"You cannot buy players previously or currently owned by your other team."
How long after I sell a player can I then purchase him?
If it's a player from the same team (i.e., your main team rebuying a player you sold from your main team or your Utopia team rebuying a player your Utopia team sold for), you can do so at any time if the player is on the market and doesn't have a salary above what your world rank allows.
In terms of buying players the other team has sold, you won't be able to ever do so unless the rule changes.