Depends on what brand actually. If RM190 for the same brand as the original myvi tyres, yes they are expensive.

Anyway, u only drove 31k km and that's about 10k km per year which is below average but not rarely driven enough for the tyres to go hard and crack/burst under stress.

Inspect the tyres, if there are no hairline cracks, u can still use it until the thread is almost worn out.

It'd be even better if u can post pics of the tyres.