For sometime I've been trying to upgrade my router extension table. I happened to find a returned countertop at the local big box store marked down to $23. This made a great tabletop. Another idea for finding a nice top
I've found sink cut outs to be great jig and table top material. My ancient rehabbed craftsman belt sander is bolted to a Hechinger blue sink cutout table top from a commercial job I worked in the early eighties. Though not from countertops, my drill press and router table are covered in Formica, top and bottom, which is far better than the melamine often used in commercial versions. Your router table definitely makes for a far nicer extension table than Sawstop's!