Ember js @each one level deep but I have a two deep level relationship

I have to access a property that is two level's deep on my controller, but the [] only can access one level deep via the emberjs guide.

model(params) {
    params.paramMapping = {
        page: "page",
        perPage: "per_page",
        total_pages: "pages"
    };

    return this.findPaged('contractf', params);
},

setupController(controller, model) {
    model.forEach(function(item) {
        item.set('sale_price', Ember.computed.alias('item.dealers_sched_id.sale_price'));
    });

    controller.set('content', model);
},

Above, I have my model which is basically fetching all records in a pagination format in the contractf model. Then I set up my controller and loop through all those models and bind a sale_price property that goes into it's relationship to get the sale_price in the correct model relation.

Now in my template, I have this:

new_suggested_price: Ember.computed('selectedItems', 'selectedItems.[].sale_price', function() {
    var ret = 0;

    this.get('selectedItems').filterBy('car_used', 'N').forEach(function(contract){
        var salePrice = contract.get('sale_price');

        if (salePrice) {
            ret += (salePrice*100);
        }
    });

    return ret/100; // We *100/100, so we avoid a floating point calc error.
}),

Basically just gives me a number that is easily format-able. As you can see it depends on the selectedItems (which is basically the model, but filters by a property). So I have to go into each model item and find that sale_price I property I set and if it changes, this computed property will update. Reading Ember's guide, I couldn't do selectedItems.[].dealers_sched_id.sale_price because it only goes one level deep.

I thought setting a property on setupController would fix that issue, but it doesn't seem to because I'm still getting NaN as the sale_price value.

Now if I set a setTimeout function for 500 ms, it populates fine.. How do I get it defined on page load?

Thank you for any help.