Definitions of 'failing' turbo run the gamut. Oil seal leakage is common and makes the repair costly but not prohibitive. The kits for oil seals run $150-200 depending on where you get them. The 'labor' is not fun, the bolts to get the turbo out tend to get rusty, and then there is the bending over...

However, your car should never smoke. I have seen blown turbos on 240/740s and they will kill mosquitoes in a 5 block area! In those instances, not only is the seal gone, but you can feel the turbo vane vibrate - new turbo required.

You do have options. Find a light pressure turbo in a junk yard and replace the seals yourself, then swap turbos so you have a running car. Find a truck (semi) repair shop that will repair the turbo, they do this all the time and might be more reasonable than a shop that wants to only replace parts.

If you continue to drive with a severely leaking turbo (lots of smoke whenever you initiate boost), it could contaminate the Cat converter and O2 sensors.

If however, you only notice smoke while going down hill and no gas applied, it could be valve stem seals. This usually happens after 180K-200K miles and is not an easy repair.
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Keeping it running is better than buying new