How to access an ArrayCollection of custom Objects in comboBox?

[artcab]

If you have an arrayCollection of custom Objects, how do you access them?
none of the following ways work:

<s:ComboBox dataProvider="{productService.products}"/>
//result: a combo with lots of [object Product]
//and:
<s:ComboBox dataProvider="{productService.products.getItemAt(0)}"/>
//or
<s:ComboBox dataProvider="{productService.products.getItemAt(0)}" labelField="name"/>

//result in an arror: Implicit coercion of a value with static type Object to a //possibly unrelated type mx.collections:IList.

I confirmed that the ArrayCollection is being populated correctly with the debugger. If you need more:

First I created a ValueObject, for example 'Product' with only 2 properties for simplicity, and a 'buildFromAttributes' function, because I plan to populate that ValueObject with XML data: [Product.as]

package valueObjects
{
    public class Product
    {
        private var name:String;
        private var cost:String;
    }

...

public static function buildFromAttributes(data:XML):Product
{
    var prod:Product = new Product(data.@name, data.@cost);
    return prod;
}

..

I created a products ArrayCollection of Product, and populated it with XML data from the server and everything is working OK since now, debugger says.

Now I want to display those elements in a ComboBox or in a List, but I have not been able. in the [mainFile.mxml]

...

<fx:Declarations>
    //Here is the service that populates the ArrayCollection, not included here.
    <services:ProductService id="productService"/>
</fx:Declarations>

...

protected function creationCompleteHandle(event:FlexEvent):void
{
    productService.send();
}

...

can you help me show the custom Product Objects from the arrayCollection in a comboBox or in a List by name or even one in a label?