Front headlight replacement

Hello. Can the bulb in the front headlights be replaced? My mechanic told me "I think the whole attachment needs to come out and be replaced and the bulbs don't come out." The part is usually over $600.00 even on Ebay and labor is over one hundred dollars. Meanwhile while I'm searching Ebay and auto part sites I'm seeing bulbs for the front headlights in my car okay in every site. Can you shed some light on this? I'm debating taking it to a Lincoln dealer repair shop instead.