I agree this child was misdiagnosed and was receiving the wrong, dangerous, treatment.
But lithium is not expensive. Lithium is dirt cheap.
http://www.coventrywarksapc.nhs.uk/mf.ashx?ID=425e5245-157c-...
> Cost: For 800mg/day lithium carbonate or equivalent, at April 2015 dm+d prices, one year’s treatment costs
> Priadel® 400mg tablets £25
> Camcolit® 400mg tablets £31
> Priadel® liquid £273