You could still use that tutorial... but it might be overkill.
The easier solution (although it requires some hand coding) would be to put the age_category and price values into the select list <option> tag with attributes like:
<option age="" price="" value="">text</option>
and then populate the age, price, value, and text from your recordset. Then add an onchange event to the select list that calls a function. That function can check the the current selection in the list and populate the text fields based on the attributes you added.