This is a picnic table design I have been building for about a decade. I have a few of these in commercial spaces that are about 8-9 years old and are doing great. For price reference, the 5′ table in the video was built in May 2020 and cost $78, tax included, for the lumber and carriage bolt hardware. I already had the decking screws and glue. I have no idea how much it will cost you in your area and have no idea how much you could sell these for. Feel free to sell these and make as much profit as you can!
To get the free diagrams and SketchUp files click here: https://jayscustomcreations.com/product/6-foot-picnic-table-diagrams-and-sketchup-file/
Here are some other tables I built in the past with the same structural design.