When you take into account editorial contributors (£100 per page, or £4,400 per issue), design and art help (£2,900 per issue), hardware, bills, app store charges etc., it all adds up.
So it's not just a "bunch of PDFs" -- it's a complicated collaboration between writers, artists and stores. We want to make it good value, but we're not just reproducing some HOWTOs. We're making new, original, creative content.
Seeing as you have a uniquely digitally inclined audience, a shortage of funds and a global market, PDFs do make a lot more sense.
I didn't mean to devalue any potential content.
Your costs are very high. There's no reason you need London overheads for an English magazine on technical content. For example, I know many first language, highly literate, technical English speakers who with extensive writing experience would be happy to edit such content at much cheaper rates than 100GBP per page. For example, 10 GBP per page. https://en.wikipedia.org/wiki/International_inequality
As for the costs, those are normal in the publishing world. Many magazines have tried slashing the contribution per-page cost, and ended up with poor quality content as a result. We want the best contributors, and they're worth paying for.
100GBP per page may seem like a lot, but that's for 800 words of highly technical content, that has to be correct, well-written, informative and entertaining. A single page can take many hours of work when you're dealing with advanced subjects. You get what you pay for.