When I needed extra outlets for my office workbench, I bought a 12 foot length of 3 inch x 1 inch PVC electrical ducting, which I mounted on the wall across the back of the bench. Then, I went to our local demolition and recycling shop and bought (literally) a bucket full of identical, good condition double outlets, fitted them to the cover of the duct, wired them to 2 circuits, and had 18 double outlets across the 12 foot wide bench. The whole thing cost under $50, and I never seemed to run out of outlets.
You may even be able to get a length of metal ducting with power and data outlets already fitted for a song if you're on good terms with the demolition man. All many of them want is the scrap value plus a bit if you're a regular customer.
(Hint: Either mount the ducting a few inches above the work surface, or flip a couple of outlets upside-down to cope with those pesky long wall-wart power-packs.)