It can be a rough business if you're not prepared for the realities.
1) It's not a no or little work business. Reality is it will be the easiest 80 a week job you'll ever have. Some weeks you may only need to be there a couple of hours a day, others it will seem like you never leave
2) As recommended, get a job at a car wash if at all possible so you can get real world experience. The guys on youtube show some great theater but leave out a great amount of the grimy reality. For example: They love to show off stacks of cash coming out of their bill
changers and claim it's revenue. It's not. The revenue is what gets deposited in the equipment. They typically don't show you when they are at the site at 2am fixing something or show you the invoice for how much it cost to have a technician come out to fix something
3) Attend several regional trade shows and the ICA show.
4) You need to read as much of this forum as possible. There is a incalculable amount of wealth to be gained.
5) You're going to need a quality distributor if you're doing a ground up build with no prior experience. Contact the manufacturer of the equipment you are interested in. In the past there were protected territories but currently the quality manufacturers will have more than one in most areas.
Without knowing your land, permitting, construction costs, what size/type wash you're looking at there is no real way to give a true estimate of cost. You could be looking at $10-$15K per self serve bay for equipment and $200-$300K for an automatic. Of course on top of that you have vacuums,
vending, water softener, water heater,
changer, etc.