Bargain Outfitters offers the 2x4Basics Workbench and Shelving Storage System, model no. 90164, for $49.49. Plus, coupon code "BH130" bags free shipping. That's the lowest total price we could find by $21. It includes four workbench legs and six ShelfLinks.
Note that only the legs, supports, and hardware are included. You must supply and cut your own lumber for this table.
Update: It's currently on backorder with an estimated shipping date of January 29.