There is no real answer to your question. Very nice cues come out of a 12X16 converted storage building that is well organized and has the lightweight machinery in it. Likewise, very nice cues come from shops that are industrial type buildings that could also easily produce almost any variety of heavy commercial woodwork.
You have to start with a consideration of what you have in the way of a building or don't have, and the funds available. I strongly recommend contacting SCORE or some of the other free services to put together a real idea of start-up costs. 85% of new small businesses fail. Of that 85%, most fail because they are under capitalized. It is recommended that you have at least six months operating capital including living expenses after you have paid all start up costs and are in business. That usually isn't possible for most of us but gives an idea of what is recommended.
Cost out the equipment to build a top quality cue with Blud, Cueman, and the handful of other specialty equipment makers, and then cost out the building to house that equipment, have working room around it, and then add fifty percent to that building size at a minimum.
I realize that this post was more about how to answer your own question than giving you a concrete answer but in my opinion you are the only one that can answer your question. I am new to cue making but I have owned or leased somewhere around a dozen shops over the years.
Here is a link to a small shop that worked.
http://www.cuesmith.com/index.php?page=shop_layout
Hu