If you have a Tractor Supply Store by you they sell "livestock panels"
...they come in various dimensions or 2"x4", 4"x4" and a graduated sizing of smaller on bottom to 4"x4" on top.
Panels are on average 3' - 4' high and 16' long. Range in price from $18.99 to $75.00. "Cheapest" is the 4"x4" opening size...which for a divider is really sufficient unless you have small ponies.
They are made of heavy welded steel, strong enough to be used for turnouts for all types of livestock is what they are made for actually.
Your local farm supply store may also have them at competitive prices.
Otherwise... the Home Depot, Lowe's route is fine but you can also do this with with white plastic pipe... not the flimsy stuff but it is certainly more cost friendly than using conduit pipe... It comes in various sizes. Here is a link to what I refer to available in Home Depot.. http://www.homedepot.com/p/Charlotte-Pipe-EverTUFF-1-2-in-x-10-ft-CPVC-Pipe-11150/202820373
Same idea though is make a frame, drill holes in the bottom strand, fit the pipe, now drill only a smaller depth hole not all the way through...the trick is lining them up.
I have a friend who did this in her barn, looks nice. She also made a spot by her feed tub that she can slide the bars up so she can dump feed and not have to go in the stall if she chooses and horses can't put their nose around a corner and get it bit from pestering their neighbor. I think those sliding bars are offset to the stationary ones, with the bar longer than the opening. She has a very nasty horse at feeding time and this was really nice so no one, animal or human, got bit or lunged at.Her barn also has the doors with the "V" gates so down they can put the head out, up they are behind a barrier gate. I after talking with my friend found out the section that moves is sitting on a second bottom board but the top board has holes cut all the way through so the entire pipe length just slides up.
Good luck in your barn building alterations... pictures when you finish your project. I would love to see the "finished look"