Hi Rich,
I got it working with the 2-step transformation approach on a single Channel into multiple different items. On the Channel I do the JSONPATH transformation to extract all price elements into a string. That string I process with a transformation profile using custom JavaScript into multiple different Number Items. 
// Transforms a string to a single element
(function(i,j) {
var item = parseInt(j); // array index as int
var fixed = i.slice(1,i.length-1); // remove brackets from incoming string
var list = fixed.split(","); // turn string into an array
var price = parseFloat(list[item]); // select the requested item as float
return price; // return the float number
})(input, item)