If you go to a woodworking store, such as Woodcraft, you can find a plethora of bar, pipe and parallel clamps from companies such as Bessey, Jet and Jorgensen. They range in price from $30 to $45 each. If you go to a box store, such as Home Depot, you can find a pipe clamp for under $20 (plus you have to purchase an appropriate sized pipe to finish the clamp).
When I took a woodworking class at the Connecticut Valley School of Woodworking, they had rows of aluminum bar clamps. They were “Universal Bar Clamps” by the Dubuque Clamp Works company. You can buy the clamps from several online retailers, including Woodcraft. You can also save money and purchase them directly from the manufacturer (USA Clamp Company). The main page of the company’s website is not working, but the pages for the clamps works. I called them this week, and they said that they took the front page down because they were swamped with orders, but they will ship clamps if I order directly from them.
The clamps are great. They don’t have as much clamping pressure as a traditional pipe clamp, but they have enough for most purposes. I will probably use the pipe clamps to glue up the thick top for the kitchen island, but that type of glue up is the exception. The universal bar clamps sit flat on the workbench, and the aluminum doesn’t stain the wood. To top it off, they are made in the USA.
Several years ago I split an order of 10 of the longer clamps (48” clamps I believe – I don’t have one of them in front of me right now). The only drawback is how long they are. That is a lot longer than I need for most glue-ups. So, this week I ordered 10 of the 24” clamps to split with one of the guys I work with.