It depends on what you plan to do. If your going to make complicated parts and/or parts in quantity, then CNC is the way to go. If your going to do "repair milling" or make one of something straight forward, then a manual machine is a better bet. As for "learning code" alot of CNC manufacturers like Haas offer training with a new machine for little or no money. I would suggest you get ahold of a Introductory CNC text and familiarize yourself with it before you take the plunge.
I didn't get into ancilliary equipment that you will probably need like air compressors, drill presses, lathes, surface grinders, etc. You'd be surprised at how quick they will eat up a budget. Also, a good rule of thumb is that for every grand you spend on a used manual, expect to spend at least 500 dollars in tooling. For a CNC machine, expect to tag another five grand onto the price for basic workholding/toolholding.
Manufacturing is an expensive, cutthroat business and costs compared to other forms of businesses are unreal. For example, the first Machine shop I worked at had one employee: me, yet they spent close to 20K a year in tooling.
If this field owner is serious, I would start getting the sales flyers from MSC, Travers, Enco, etc and start watching Ebay for tooling costs and machining costs respectively. This way you can present them with an accurate budget of what this will cost - the number one killer of new businesses is undercapitalization. It will also show them that your serious about your commitment to it. I would also suggest you demand to be a partner, not an employee - yes they have the money, but it will be your time and skill that will make this a going side concern or not. Plus emloyees are all too easily replaced - you don't want to be dumped after you get it up and running do you?