What should I trade for a closer?

My closing is terrible lacking with Dotel, Street and Reyes, and my offence is pretty solid with Pujols, K. Johnson, Braun, Tejada, C. Lee, Hart, and Chris Young, with Atkins on Util, I have Pena on the bench and i alternate him with Atkins. Should i trade for a closer like Rivera and possible Nathan? and with whom? (btw the other manager is willing to do 1 for one trades)