Cutting down production costs on children books

Hello All,
Today I'm not writing a new story but rather an episode in the quest to cut production costs of the children book I am writing and now want to get published.
I would like to publish a book with low costs to make an affordable book at the bookstores. This seams to be a quest on it's own. When I setup this journey for writing a book I did not imagine to find so many little problems that an author most overcome, especially a new author.
This time it's about production costs, which in my belief, for children story books is really of a big impact. From what I have researched, the format of the book has high impact on the costs. It seams the printing industry is optimized for landscape books, which is fine for novels and the majority of the books, but I do not find fitting for children's books.
In my experience, more as a father than an author, the landscape book has a huge advantage for reading a story to little children. You open the book with your child beside you, at the sofa, at bedside getting them to sleep or a long trip in a plane or train. This makes it comfortable if the book is landscape, you can have a one page with the picture or drawing to capture their attention, while having the text on the other page in big letters for you to read.
So I have been betting quite a lot in landscape format for the book. While I was making the mock-ups I did not realize this format problem, basically the mock-up is so expensive that you do not note a difference between 4 euros in a 50 euro book due to format change. Well, for the final mass printing book you don't want to have costs of 50 euros, you should target 4 to 6 euros tops for the production of your book, to be able to have margin for warehousing, distribution and have some royalties left.

I made an attempt at producing a new set of mock-ups reusing the materials I have produced so far in one of the cheaper color production formats. The results can be seen in the picture.
Not counting the fact that I had to crop all the drawings so far to capture the essence of the paragraph, it is not a suited format for telling a story to a kid. It seams OK for a children's book targeting the age from 8 above where the child reads the book on it's own, but definitively not for the sharing experience between a parent reading the book to the child.
The book printers, the distributors and the bookstores  are prepared for several sizes, almost all of them for black and white portrait books. Well, I neither want black and white, it is not appealing for a young child, nor want a portrait book, not suited for the shared reading experience. Therefore I have to limit myself to what is available for mass printing int the color landscape books.
So for you new authors coming into this area I share with you the suitable formats I have found so far. If you want color landscape the only format I have found so far is 8.5x8.5 inches (21.59x21.59 cm), which is not landscape, but being a large square can be suitable for the shared reading experience. There is another format that book printers support which is 8.25x6 inches (20.955x15.24 cm), which is landscape but unfortunately not an industry standard, which limits you the availability of selling in some bookstores. If you can live with that limitation then that would be a good format.

In the mean time I did receive also the mock-ups for the new revised and simplified text with the change in the drawings to get more colorful and cheerful and am quite happy with the results. Nevertheless I believe the text can be further simplified, and the drawings need to be revised to accommodate for the square size. I do not want to have a crop to the image that loses something that we wanted to transmit in the drawing.
But another warning for the new authors, especially for the illustrators, you need to account for something called bleed. This is the margins where they cut the paper, so if you want the picture to be full size of the paper or to not get any borders there, you have to account for the bleed. This means that you have to account for an extra 0.125 inches (0.3175 cm) that will be cut off. If you want a full size page with a picture than you need to account for that extra top, bottom, left and right.
I do believe that if you are a renown author you will not have any of these limitations, but if you are a new author, or intending to be one like me, then you need to account for all this industry optimizations as to avoid incurring into a lot of the extra work I am having because I did not know these things from the early beginning. The curious fact is that this applies mostly to children books!
Well, now back to work, I have many drawing to remake, the good thing is probably they will come out better than the original, so not all is that bad :) And the story is a Christmas story, so we still have time for the correct selling opportunity.
Thanks for all the support all of you have given me, if anyone of you knows a thing or two about the problems I am having and would like to refer to their solutions, I am more than happy to receive your feedback.