I know that there will be some amount of cost and a publisher must get a return on investment. You may want to do a poll to get an idea of how many people and libraries (for I believe that the libraries will be the biggest buyer) would purchase. Also if you all don't have a complete set of the older magazines, some people may be willing to part with theirs for a copy of the electronic one (I know I would but my collection is small). Please note that in order to get a good copy they will have to take the magazine apart. So no one should expect their old magazine back.
Some would argue that they only want the paper magazine. Paper is great and I want my new magazines to come to me in that form so I can read it where every I want. But after that an electronic form is better for space and they will not deteriorate with time. Also if you want a copy of an article you can print it from your computer. Some of my older magazines from the 30s I'm afraid to open for they may come apart in my hands. On current magazines, I would love to see a whole year publish in electronic form that can replace what I got (I give away duplicates now to people to get them instrested in the subjects).
Any way good luck with the idea and I hope you can sale it.