I agree with Jim, you can make a good bench with lumber yard dimensional lumber. There are a lot of good plans floating around on the internet that use dimensional lumber that is simply glued and screwed together. Not everyone has to have a Roubo :) The most functional part of the workbench will be ensuring you have a good vise and that the bench is solid enough for the work you do.
Making a workbench is a great project to expand handtool skills; it’s a lot of work but great experience at jointing and planing for the top, as well as doing some large mortise and tenon joints for the base.

Rob, Sault Ste. Marie, Ontario