The combo kit is initially $489.00 for the M18 18Ga Brad Nailer, Hammer Drill, Impact Driver, and (2) 5.0Ah batteries. On the page, you can add a "free battery"; when added, the cart will break out the combo kit to $380.77 and battery to $108.23 (keep in mind the kit already comes with (2) batteries). The separate battery can be returned to bring the combo kit total to $380.77 + tax.
For reference these typically go for: Brad Nailer - $279, Hammer Drill - $149, Impact Driver - $139, and (2) 5.0ah batteries - $139 x 2, for a total retail value of $567 (tools) + $278 (batteries) = $845. Instead, you're getting each tool for $100 and each battery for $40, and this is doesn't even count the charger and hard case.