It's normal for there to be in and out play in the axle CV joints. They are designed to move in and out as the car moves. What you do not want is play when rotating the axles back and forth, nor should there be noise from the axles.
But it's true that if the boot is torn, and it's been torn for an unknown period of time, it is likely best to consider replacing it.
I've had good luck with re-manufactured Genuine axles from CVJ axles. Google them. You will need to return your axle as a core to get $75/axle back. Quality is good, though, and the price for each axle is not much more at all then the aftermarket knock-offs.
The job is generally straight forward. You will need to re-fill the differential with fluid as replacing the axles involves draining it and removing the rear cover.
You will also want to consider replacing the seals on the side of the differential. Even if they look good when you remove the axle, there are reports that they will begin to leak shortly after installing the new axle. Corteco OEM quality seals are inexpensive, so it's good insurance to replace them.
Otherwise, the only real consideration relates to ensuring that upon installation there is no play of the axle end that enters the differential. There are shims that will be re-used; if the axles don't fit snugly when the c-clips are installed then a different size shim will be required. vstech has recently mentioned he has lots of shims available, so you can contact him before you go to the dealer for parts.
Here is a DIY guide:
PeachPartsWiki: Replacing the Rear Axles