I see in a photo that there are 4 portlight frames on an Apache so I understand why you would want aluminum. I would guess that they are fairly expensive to fabricate but who knows? I have had metal parts fabricated before and they have never been cheap. 4 new ones in wood as jarcher suggests or starboard (plastic) are probably less expensive than 2 in aluminum and you can make them yourself if you are handy. Or maybe there is a trade school in your area that would like to take on a metal project and build them for you.