If you are planning to make money from a CNC, you will have to become very good at marketing your services. Translated, that means being very good at identifying and effectively contacting people and businesses that are likely to make good use of your services. Everyone and their uncle Tom is making occasional signs, or signs with clever sayings or even images they hope to sell in consignment shops or weekend craft gatherings. But to really make any money, you have to identify markets that need lots of what you have to sell, but not so many that they go to a completely automated shop, or one that markets and jobs out the work to Mexico or Asia.
One example would be a small chain of regional hotels with a homey feel where signs, plaques and things of that sort , in script or with logos or other identity setting features are needed in fair numbers.
As machines go, that means something pretty fast with easy setup and software that makes such things as using special fonts or logo images easy to set up and produce in limited runs. In marketing, you'd probably have to locate, contact and work with art directors, architects and interior designers -- the real buyers.
With really good software, you could locate individual property owners for inns or mountain cabin owners, whose orders would be small, but beyond hand made sign quantities. Entrance, exit, mens, family and womens' bathrooms, room number, breakfast, meeting room and other signs with logos and unique fonts are all possible products.
I teach marketing to eye doctors, and know how important it is to any business. The internet and social media are good places to search, and 150 to 300 searches will turn up a good number of customers. You don't want to just have one big customer, they apply intense pressure to cut prices and profits. A good mix of lots of medium sized repeat customers is essential.
Deliver as fast as you can. Get all art approved by several people. If you see something odd or off in the design, check it with the customer before you make it and try to provide a proof run before you produce in quantity. Learn to proof read. Check the spelling of every word and if any problem shows up, check with the customer before starting design or production. These kinds of projects seldom get full attention and you backing up the person who orders this way will save their fanny if you catch a problem before their boss does.
Check out all kinds of materials to use for projects. See if you can find sources of cutoffs that are consistently available. For example, my son in law gets large quantities of 2x6 asian hardwood from pallets used for forklifts.
Make your laptop the center of your business rather than the CNC. Being able to sit in your car on vacation while handling a design shows up as exceptional service, and pays for the vacation at the same time. Plan for rush orders. Designers are notorious for pushing deadlines and giving the producer precious little time to finish. That is a formula for a designer who makes an error to blame the producer for errors and delays, and to cut you off. Make this attention to detail and possible "inconsistencies" a feature of your service. You've got your customer's back. If necessary, run everything by a skilled proof reader before submitting the final design to the customer for approval. It's no fun eating a $2,000 order because of a missed comma or wrong font.
Do not make the mistake of competing on price. Start as high as you can stand it, then go up another 10 percent. If you slash prices to below market rates, you can be dismissed by competitors merely by their saying, "you get what you pay for."
I know free advice is easily dismised, but I've been doing and teaching marketing for 35 years, and charge a lot for my recommendations. If I were in your situation, what I suggested is what I'd do, and I'd have a list of 30-50 high potential 50-signs-or-more customers in hand before I put a penny down on a machine.
And, I really like that entrepreneural spirit and a couple working together as well.