Plus who says the used engine will last 9 months. Also, if you think the cost of the engine is all it will be then think again. As you take the engine out and reinstall another you will come across something else to be handled while in there. If you need something quick then find a small used car to buy and drive it for 9-12 months while you do the other engine because your engine swap with the used one will likely get a hang up or two while doing it. Again, like undy said, your money......