It is nice when you can just get one from another car at the junkyard, but the self serve yards treat cars like cattle. Cars are picked up by careless forklift drivers and the shafts are most often bent. Even a 1/4" bend in a shaft will result in serious vibration and early U-joint failure. The best move really is modifying your original. The driveline shop I deal with charges around $100 to cut, balance and install 2 new U-joints. I consider it a part of any car build or axle swap nowadays.