how much do they cost
Prices vary, depending on vendor. Do a Google search for "drug testing kits" and compare prices.

and what is the first void of the day mean?
Void is another name for "pee". Like Deige advised, use the first void of the day when doing your home tests. The first void of the day carries the largest THCA concentration. If you test negative using the first void of the day, then youre good to go. :thumbsup: