First you're talking about driveshafts, then your talking about axles. First of all, the driveshaft isn't your axle shaft. If the shop told you your driveshaft needs rebuilt, then probably the CV joint at the top of your front driveshaft is making the clicking noise (mine was just doing that too, I rebuilt it). The CV joint is made up of 2 U-joints. Sometimes one of the U joint end caps wiggles its way off, then the joint gets sloppy and clicks.
If you are mechanically inclided to do so, you can go to Autozone and buy 2 heavy duty Brute Force sealed U Joints. They are $15 each. Take out your front driveshaft completely. You'll need a vise and a hammer & a big reg. screwdriver. Look at the CV to see what's wrong, then remove the keeper "C" rings. Put the shaft in the vise and pound out the end caps from the inside forcing them outward. Remove the joint. WATCH FOR LITTLE SPRING on the inside of the CV... don't loose it. Remove both U joints, and pop the new ones in place. Once again pounding the end caps ON VERY CAREFULLY from the outside (I use a socket to pound on). Don't disturb the roller bearings inside the cap. Oh yea... and use good grease inside each cap. Once together, replace new keeper rings, make sure they are seated all the way. Then wiggle the joint around to free it up. You may have to beat it off the workbench to get it moving. -OR.... PAY THE SHOP $100 to do it.