dataBinding and atributes

[jAQUAN]

yep, me again.

I'm following the tutorial here.

It's working fine for me, but I need to extend it a little and I can't seem to find any documentation on it.

Basically, my PHP is sending back an xml string like this:
<results>
<row>
<artist>artist1</artist>
<song>song1</song>
<price cost='99'>clickme.swf</price>
</row>
</results>

I have the HTTPService's result tag call a function named bsResultHandler() shown here:

        private function bsResultHandler(event:ResultEvent):void{
            // Save a reference to the list of bloggers
            resultsCol = event.result.results.row;
            trace(resultsCol.toString());
            // Hide the busy cursor
            CursorManager.removeBusyCursor();
        }

My DataGrid's dataProvider is resultsCol.

How can I get one of the DataGridColumns to show the value of cost?
right now I have:
<mx:DataGridColumn headerText="Preview" dataField="cost"/>