It doesn't matter how much money you throw at/waste with it. The knowledge and skill has all but left for greener pastures. The boat has sailed.
I'd still love to know where this "couple of hundread thousand pounds" came from for the Iyonix II. The number is just... fantastical.
Not making a living out of RISC OS? That's because there's no money, and the last remaining users throwing their savings at developers will not help the long-term problem. You might get a new product. And then you'll be back where you started. Why bother at all? RISC OS will never, ever become mainstream again.
I don't know what the size of the RISC OS economy is, but I would be truly astonished if it were anywhere near £100,000. Even including some dealers' fabulous prices.
Thus, money is not the answer. As you yourself say, RISC OS is a hobby platform. You don't keep trying to keep it alive by poking it with sticks of cash, you keep it alive by getting people interested again. How you get people interested again is the problem.