Bryan, if you can veneer a raw MDF cabinet, you might as well build a cabinet yourself. Veneering is harder than the cutting and glueing MDF. And you'll save yourself at least $100 between parts and shipping. MDF is cheap. Heck, you could go to a Lowes or Home Depot and get them to cut the cabinets to your specs, then glue them together...the port tube is easy, just countersink a circle cut 1/4 inch or so the width of the port tube thickness and stick the port tube in that ring hole...apply goop or whatever. the port tube length plus thickness of cabinet to the outside should be 6 inches.

You could probably find people to make the cabinets for you.

I'm doubtful you'll ever find a cabinet the same size on another site. Most cabinets are a generic volume (ie: 0.375 cu ft) and aren't customized like these (0.338 cu ft). The closest I think you could find would be these at parts express, but changing dimensions will alter the sound of the speaker.
http://www.partsexpress.com/pe/showd...number=302-712

The Madisound cabinets are probably the way to go...and, Madisound uses better parts for the crossover...(or better yet, buy the pre-made xo's).