I’m going down the path of incorporating t-track in my waste board, and found this: http://www.orangealuminum.com/t-slot-framing-systems-and-tracks/t-track.html .
Having previously used t-track from other suppliers, this is the lowest price I’ve run into - $6.92 for a 3-foot length, plus free shipping (US) on a $100 order. Another plus is that it comes pre-drilled every 3".
Note that it is thicker than the other track I’ve used (.490 vs .375). The plan is to use alternating lengths of 3/4" MDF between t-tracks, fastened directly to my table, and using a 3/4" dia. spoil board cutter to level off the surface of the MDF.
Eliminating the extrusion under the waste board will allow me to gain another 3/4" (20 mm to be precise) of z-axis clearance for carving thicker stock. I can always layer smaller waste boards on top for thinner stock.