You can get started with a used machine or two (from about $4000 to $8000), a used enclosed trailer to hold your stencils, equipment, cones, supplies, etc.... for about $1000, Stencils will be about $400 to $1900 depending if you can find any used, probably have to buy new, the number sets are expensive.
You can get by with one striper but it is better with 2 of them so you can have dedicated color machines as sometimes it takes some flushing to get the color out to change colors.
Solvents will cost you about $40 to $65 for each bucket of solvents used to clean out the machine after each job so you can store the machine, you will use up about a gallon or so each clean up. Depending on the paint used, you will have to use different solvents like mineral spirits, Xylene, lacquer thinner, MEK, etc.. to clean up the machine.
Cones are cheap and barricade tape is not too expensive to block off areas of the shopping center or parking lot.
Tape measures from 30' to 300' will be needed, protractors and other layout tools will be needed for new layout jobs.
Marking chalk will be needed to mark off areas for new layouts or to mark lines that are badly faded.
There is more but should help you get an idea.