Unless your son is already demonstrating an aptitude for making/saving/investing his own money into business-like activities (you've made no mention of this) and discipline to match, it is way the heck too early to be thinking of/encouraging him to start a business of his own after graduation. In fact, I don't even think you should be presenting it as an option to him, and in no way should you be thinking about setting aside the 200k nest egg in order to purchase a business for him. That doesn't mean you have to pack him off to college against his will (and it's also way early to think that he might be opposed to it-- there's a lot of excitement he can get swept up in his later high school years as his friends and peers start prepping for their college lives.) There are lots of options. But I really don't think 'becoming a business owner' is a good one.
I don't know if you & your spouse are small business owners yourself, but there is a sort of glamour and prestige to ~being a small business owner~ that people like to talk up. Hey, isn't it nice to set your own hours, own your own [insert the blank], be the boss? As a small business owner, I don't work for The Man, I work for myself!! Who needs a ridiculously expensive degree when you can just Own Your Own Business?? That sort of thing. But the fact is, most small businesses fail. Some of them fail small, they make enough for the owners to live on and run their course. Some fail big and cost their owners tens if not hundreds of thousands of dollars, years of their lives, and loads of stress. Even the successful ones can be a ball and chain upon their owners. Businesses take money, dedication, tons of hard work, experience, and a lot of luck to succeed. You can provide your son with only one of those things-- he has to be willing to learn/work on the rest.
You ask 'what preparation and experiences should we encourage?' I actually recommend a customer service type job-- yup, receptionist or food service or retail. One where he's going to need to deal with people from all walks of life and learn to deal warmly and professionally with them-- and a really important skill for business owners because they need to deal warmly and professionally with employees, customers & clients, even the shithead ones. In that same vein, encourage him to take charge of his own money, whether it's allowance or wages. Teach him the value of tracking every bit of it, saving, investing, and spending smartly in ways that maximize the benefits he gets. Business owners are always faced with the question of what to do with money they've earned-- what do they keep, and what do they reinvest into the business? How can they invest in their business to maximize their profits/make their lives go more smoothly?
As a personal example, I run a... I hesitate to call it a small business, lol. Maybe more like a micro-business, just me making crafts and selling them to the tune of ~30-100 odd orders a month. And even that takes me a ton of time and energy, research into popular trends, networking, familiarity with my market, managing inventory and supplies. It's great... but only because I love what I do, and I actually enjoy both the creative aspects and the monotonous parts of my business. And I'm also only able to do it so well after plugging away at an ordinary office job for 7 years, learning from my company's successes and failures, and seeing firsthand the disastrous results that come about from a lack of tracking and organization. Similarly, whether or not he goes to college, starts a business, becomes a tradesperson, joins the Peace Corp, or whatever-- the keys to success depends on the skills your son wants to learn for himself.
