So what I understood, I can just make a request for certain design of a board and certain microcontroller that I want to use, also ICSP header on a board so I can upload program myself?
I would have to pick one of ATmegas since I wouldn't want to modify my code or even to write it again from scratch on some assembly like language.
328 would be a good price for me and It would work perfectly, but fact that no commercial products (other than arduino) use 328 worries me a bit.