Dude you can just rebuild the boot if it is just cracked, I should rephrase that you can replace the boot! Also are you sure he meant CV joint and not the lower ball joints. They are two entriley different things, dont let a mechanic screw you! If it is the lower ball joints you can get those replaced for free by mitsubishi(there was a recall). I got both mine replace and got them to throw in the CV joints for free. I had a mechanic freind tell em "due to stress caused from the worn ball joints the cv joints need replacement". If you got a mechanic freind go for it.
Also are you sure he meant CV joint and not the lower ball joints. They are two entriley different things, dont let a mechanic screw you! If it is the lower ball joints you can get those replaced for free by mitsubishi(there was a recall). I got both mine replace and got them to throw in the CV joints for free. I had a mechanic freind tell em "due to stress caused from the worn ball joints the cv joints need replacement". If you got a mechanic freind go for it. 
