Amazon offers Prime members the Paper Mate InkJoy 100RT Retractable Ballpoint Pen 20-Pack in Assorted Colors for $5 with free shipping. (Non-members can bag free shipping by checking out with Subscribe & Save; Staples offers them in Assorted Colors or Black for the same price via pickup.) That's tied with our mention of another color from three days ago and about $3 less than you'd expect to pay in local stores. Each pen features a 1mm medium tip.