http://www.lightake.com/detail.do/sku.Ultrafire_3.7V_880mAh_CR123A_Rechargable_Battery_(2_Pack)-27032 x2 @ 3.35 = $1.68 per cell
http://www.lightake.com/detail.do/sku.UltraFire_ICR_123A_3.7V_880mAh_Rechargeable_Battery_(2_pack)-25255 x2 @ 3.73 = $1.87 per cell
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Always remember , the easiest thing in the world to do , is to expel hot air from your lungs and through some vocal chords ..
The resulting sound may , or may not be worth listening too ….