A car kit works as a work kit if you can still get outside to the car, assuming you are in an office. If you road it, as I used to often, then you put a car kit in the work vehicle. The beauty of this is that there's plenty of room for you to work with, even if all you have is a cubicle. A cheap duffle bag full of the requisite clothing and gear for sheltering in place even if the power's out, a drawer full of food and first aid supplies, and a flat of water bottles is practical (I had a similar setup in my cubicle in New York).

The point is, use what you have, and invest where it will make the most difference for the dollars you can afford to spend.