<select id='bill_to'>
     <option value='a634jhj2'>test@c.com</option>
     <option value='agfd4ghj2'>test2@c.com</option>
     <option value='asdf634jhj2'>tes3@c.com</option>
     <option value='agf2342d4ghj2'>test4@c.com</option>
</select>

$('#bill_to').find(':selected')

$('#bill_to').find(':selected')

<select id='bill_to'>
     <option value='-1'>Select<option>
     <option value='a634jhj2'>test@c.com<option>
     <option value='agfd4ghj2'>test2@c.com<option>
     <option value='asdf634jhj2'>tes3@c.com<option>
     <option value='agf2342d4ghj2'>test4@c.com<option>
</select>

<select id='bill_to'>
    <option></option>
    <option value='a634jhj2'>test@c.com</option>
    <option value='agfd4ghj2'>test2@c.com</option>
    <option value='asdf634jhj2'>tes3@c.com</option>
    <option value='agf2342d4ghj2'>test4@c.com</option>
</select>

$('#bill_to').find(':selected').val();

var selection = $('#bill_to').find(':selected');
var really = (selection.attr('selected') != null);
var selval = really ? selection.val() : "";      /* or null or whatever */