Yea, Alan's are awesome but the whole lower was fiberglassed and he currently doesn't want to do any others.
I went the easy way, just made a new lower portion from MDF and fit a speaker onto it w/a cover over it, and painted it to match the interior color scheme:
I too made a new piece for the bottom of the door out of MDF, then recovered them with the same material my seats are done in. Speakers are 5.25" Polk component speakers.