Maybe you don't need a built-in. I have a 6' long, 2' wide workbench in my garage (Home Depot) that has room for 2 rollaround cart with tool drawers underneath. I've got a grinding wheel/polisher bolted to it, a belt/circ sander, and a small drill press on top.
Check out his nice looking workbench at Harbor Freight:
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Yukon 60" item#58832
I have this one in my man cave for do-it-in-the-cool projects.