Historically, the estimated cost to bring an injected model kit into production has been 1000 dollars per part of the mold. The bulk if this would cover research, master, and cutting the mold die. Artwork, instructions, and decals are small side expenditures. The plastic itself is cheap, 25 cents per pound.
Even if you consider the modern differences of using CAM to do your master & cut your die as opposed to building a physical model and pantographing the die with cutters. There is still a time and money expenditure. You have just changed the speciality of the artist. Whether it still takes 1000 dollars per part, or it now costs 1500 or 500 because of technology is irrelevent. The average cost per part is a constant.
At half the scale (plus or minus) you are now twice the size. What was two or three parts in 1:350 will now be four to six. Look at the parts count expansion for a quad forty MM from 1:700 (two) to 1:350 (five). In 1:200 scale I can identify at least eight to ten separate pieces which make up the assembly.
So your unique piece count becomes your cost driver. You make more and more detailed parts because you can, and that is what the modeler would expect.