Amazon has 4-Pack Pentel Twist Erase Mechanical Pencil w/ Eraser + Refill Lead (0.5mm or 0.7mm) on sale for $3.97 listed below. Shipping is free with Prime or if you spend $25 or more.
Note must be sold/shipped by Amazon
4-Pack Pentel Twist Erase Mechanical Pencil w/ Eraser + Refill Lead (0.5mm) $3.97
4-Pack Pentel Twist Erase Mechanical Pencil w/ Eraser + Refill Lead (0.7mm) $3.97