Power Train Driveline problems of the 2006 Mazda Tribute

I am the original owner of a 2006 Tribute. At just under 50,000 miles the abs light came on and the 4wd started flashing. The dealership said it was the ring on one of the front axles. Turns out it was the passenger side. Now, just last month, at about 70,000 miles the lights and flashing started again. This time it was the driver side axle that went bad. We have also had to replace both u-joints. Even worse, the area dealerships said we needed to buy the entire drive shafts to fix the problem; they're about $800 each because Mazda does not carry just the u-joints. The first parts store we called had them in stock and they were $23 for both.