Great info in this thread. We were in a similar situation as you with a slightly larger shop.
I would completely agree to evaluate your current production numbers and what you feel you can do with increased production.
Two years ago we brought in a CNC and the numbers tossed around here were what we had in mind however they didnt turn out to be completely accurate and a tremendous amount depends on your current shop and equipment. We for instance had no intention of investing in a $70K machine (purchasing new not used). I would disagree completely with buying a light $20K base line machine if your talking about any volume of production (several hours per day and several days per week). I think at that level you will soon find yourself wishing youd invested in a more robust machine and either living with a less than adequate machine or having to deal with selling, swapping, and upgrading. We went with a machine in the $50K class (10HP spindle minimum, and all the tool changer you can afford would be my advice). We wanted a domestic machine with heavy steel construction and went with ShopSabre and couldnt be happier with zero issues in 2 years of heavy use. The machine is exactly in the sweet spot in Pauls post at 60x100. The 60" would be the minimum for us. A 10' machine would be nice but we havent found ourselves needing the extra length.
We opted to upgrade our air and run a dedicated collector for the CNC so our total outlay with the CNC, air, refrigerated dryer, filter, electric feed to the CNC, an moving an existing cyclone over to the CNC, sofware, and an initial tooling budget, as well as a good bit extra cushion for initial operating, was about $75K total.
If we opted not to upgrade air, or didnt run DC the way we did, we could have easily lopped 10k off that number. Eliminate the cushion and a bunch of other gee gaws we tossed in would chop it even further.
Its a monster investment for a small shop and I dont know how varied your work is (ours is extremely varied) but when you get to thinking outside the box with the capacity of CNC its impressive the non-standard things you can shift to the cnc and drastically increase productivity. If your primary work is going to be fine with less expensive, dedicated boring, that would likely be the best route.
While Im not sure the Cabineo is an across the board production solution, we have now done several jobs using them and they are a really impressive little RTA fastener. We literally just shipped a job with them this week. I dont think they will replace boring and case clamps but they make very nice cabinet and are surprisingly strong. We did a destructive test on a box when we initially brought them in and they are now our go-to knock down fastener. The single face machining is great and ripping fast. They are great for field assembly or by the end user.