Although there are a few storm chasers that chase as part of scientific research, or run storm chasing tour groups, most storm chasers sell DVDs to make up some of the storm chasing costs. Some storm chasers have been lucky enough to appear in documentaries where storm chase expenses are paid for and gain some publicity.
In my situation, the early years were virtually 100% expenses. With increased media publicity came more opportunities. At least now storm chases are mostly paid for taking the burden off the thousands of kilometres spent on the road and the rising fuel costs. And of course all of those air fares and accommodation costs whilst overseas. The sales of storm DVDs and video stock footage assisted in making up some of my immense costs. Perhaps the most significant were the sales of the Australian tornado stock footage given it is was a significant event and very unique from up-close.