If the boots are badly torn and the previous owner put alot of miles on the car then I would deff. recommend you replace the axles. Your mechanic should agree. If road debris gets inside the torn boots it destroys the c/v joints/ knuckles.

It is a lot easier to replace the shafts then to fight to get the boots on and off. This way the knuckle wont get distrubed.

 

For our cars, you can just but the outer CV replacement kits. You don't really need to replace the whole shaft.