With the advent of digital publishing, printing on demand has become very common and as a matter fact it has become the norm. Primarily it helps to economize the book publishing business model as it reduces the number of books to be printed because conventional printing press will require at least 500 or 1000 prints otherwise it becomes uneconomical commercially. However, your query on two colors printing restricted to black and red colors appears very specific and also special. Generally, publishers categorize book printing either as black & white or Color printing because color printing is almost 3 to 4 times expensive especially with digital technology, unlike offset printing where this can be done cheaper, especially for multi-color, because you can print black & white on a cheaper printing machine where the bulk of the printing will be done and only colors which are normally photographs or pictures involving few pages can be processed on the costlier multi-color printing machine.Therefore the costs of conventional printing method come down drastically compared to digital multi-color printing which has to be processed by a single machine and with digital processing, the capital costs are very high as well as the labor costs because the skill levels to operate the software is high and therefore salaries paid are also high. 396
As far as my knowledge goes I think the red and black color will be classified as multicolor as two colors are involved and therefore it does not reduce costs and will be as expensive as multi-color printing compared to black and white in digital printing and publishing. Therefore in the conventional method black and red color printing would be comparatively cheaper to digital technology but the main advantage with the latter is the savings in terms of inventory and storage space and avoiding the unnecessary burden of unsold stock which is waste of natural forest resources and this cannot be avoided in the conventional methods because the economy of the batch size and therefore a substantial volumes of paper cannot be avoided due larger volume of printing. Therefore you have to take a decision based on your willingness to accept the costs of digital color printing versus conventional method and saving the wastage of paper from the ecological perspective. Hope this gives you adequate explanation to take a decision. 396