Most important, with cost consideration
1) Vehicle
2) map, weather radio. (<50 dollars)
3) Laptop + wireless net + radar program + GPS. (low end: 400/25mo/75/125)
Really, not too much overhead for a new hobby. People used to make a go of it with 1&2 for years. So, have those at the minimum.
I'd say the majority of the people here that put some serious time in chasing have one two and three.