@jpsawyer I've tried that,

var subList = itemRecord.getSublist({
        sublistId: 'price1'
    });
    log.debug('sublist', subList);
    var subListValue = subList.getSublistValue({
        line: 0,
        fieldId: 'pricelevel'
    });

But I get an Error, TypeError: Cannot find function getSublistValue in object sublist.Sublist.