As big-box stores struggle to meet the lowest of earnings projections and shutter dozens of stores nationwide, one type of brick-and-mortar retailer is thriving: the dollar store. Hollar, an online dollar store launched in November, has seen 50 percent month-over-month growth for six consecutive months. By April, it had reached $1 million in monthly sales. Part of Hollar’s success is offering a convenient way for moms to shop from their mobile devices. Today, the Santa Monica based company is announcing its plans to manufacture products of its own.