(George Walker IV/The Tennessean via AP, Pool, File)Shopping on the NFL free agent market can be so very tempting. Just ask the Tennessee Titans. Busting on free agents doesn't stop any NFL team from trying again. CORY LITTLETONThe Raiders thought they were getting a difference-maker when they signed linebacker Cory Littleton to a three-year, $35.25 million deal. STEPHEN WEATHERLYWeatherly was a major bust for the Carolina Panthers after the defensive end signed a two-year, $12 million deal last offseason.