Aihe: Dead Teams

Hello from across the pond. I have a question I was hoping one of you may know the answer to:

Once a team folds.....can you bid on the free agents? Sometimes I see free agents for sale from these teams. In other situations their free agents do not go onto the market? Is there a certain timeframe that these players are available? If not, are these possibly great players just destined to rot on a folded team?

Thanks for any input,

HH