We need to get a NY member involved for some stste required specifics, as I'm across the river in NJ
How much $$$ to start-up?? Depends on what you want to get involved in. Truck, tools, office, phones, stationary, "shop", etc., etc. I started from the house, 1 van, lone ranger, found a used truck, hired 1 guy; continued on a little at a time.
Resi don't require a lot of "special" tools, but comm & industrial require either a rental account, or an investment. (Bender/puller/punches/crimper/meters, etc.)
Insurance is a BIG $$$; Business liability, workers comp, 4 trucks, and the F700 Bucket run $25k. Medical is another issue; 50% for my employees, (Blue Cross/Blue Shield)10K+/-
Business Liability insurance is mandatory in NJ, you need a certificate to obtain a Business Permit (at a 1M min. I think.)
I keep office expenses at a minimum, and use "Quick Books" for billing, payroll, bookeeping, etc.; have an acountant, 4 times a year +/-$1500.00
THen there is fuel, maintenance, payments for the trucks/vans.
Don't be alarmed, a whole bunch of us guys did it, & survived. Lastly, expect "some" payless paydays as the boss/owner.