I have used pipe clamps for a long time. You buy the heads, and then go to Obi or Baumax or somewhere similar and buy the pipe. You can get the pipe easily enough in various standard lengths, and you can swap the heads between short pipe and long pipe very easily. If you want to clamp them in a vise, you make a couple of false faces with a notch in. Go for the larger, three quarter inch versions, they flex less. These are also easier to add to a bench bull, as the pipe is round, rather than rectangular.
Check out the Fine Woodworking ‘New Fangled Workbench’ to get some inspiration.