A quick internet shows glass vial weight of 27g for a 30mL (i.e., 1 oz) container. 27 grams is 0.95 oz. So for a potion vial with 1 oz of liquid, the weight of the vial itself is 1 oz, total weight of 1/8 lb (0.12 lb).
Similarly, the glass vial weight is 108g for a 120mL (i.e., 4 oz) container...