Much cheaper than McMaster and these are also good quality, I have them on my printer.  You will need a dremel with cutting wheel to trim them to size.  Also, you will want to upgrade to linear bearings with Lawsy carriages at the same time, the stock bushings will not work well on these.  But if you must stick with the stock bushings, I have the old SD3 stock rods that I could sell you for cost of shipping.  But don't do that, the smooth rods with bearings are a great upgrade.