Fruil makes the best Bradley tracks, both the early style (ATL-78) and late style (ATL-79). The M2A2 would normally be seen with the later style today.
AFV Club makes the late T-158 M1A1/A2 tracks. Armour Track models makes both early (T-156) and late (T-158) tracks. No one makes the latest T-158LL tracks yet.
AFV tracks are recommended and run between $15-20. Fruil tend to run in the $30 range as do Armour Track models.