When rehabbing houses, I just remove the window, take it down to the local glass company and have them replace it. They have all the correct tools, sealants, etc and can generally turn it around in an hour. If there is damage to the trim pieces of the window, it can take a couple weeks for them to order the correct parts if they are unable to make the piece themselves. The last window I took down for a broken pane (that I poked a hammer through while siding the house) cost me about $40 in parts and labor to fix.