I'm not an expert but the obvious solution is to give the Oxford/AstraZeneca vaccine to the 18-55 population and the mRNA vaccines to those 65+. The mRNA vaccines also have stringent and extreme freezing requirements that the Oxford one doesn't.
Moderna's vaccine's refrigeration requirements are not extreme. It just needs -20 C (i.e what a kitchen freezer can do) for shipping, and then will be good for a month at 2-8 C, i.e. kitchen fridge temps.
First of all, your "10x the price" means a price point between 10$ and 50$. That's hardly a blocker.
Some people, when facing the choice of having a shot at a vaccine sometime in the future and have a reliable vaccine right now, would gladly pay 10x to speed it up.
