I have an 89 325i vert that needs a new back window in the convertible top. The top itself is in great shape. I just got this car two weeks ago and need to do timing belt replacement and all that goes with that ... plus I have other things I want to add to the car. I can replace the back window plastic with a kit from eBay, but I am not too handy with those things and am afraid the window will not work. A new top is over $400 plus installation ...easily $1000 or more. And I really don't need a new top.
So, what would you do? Your advice is appreciated.

In this order:

1. Plastic window remedies with polish - perhaps it can be rescued
2. Replace window plastic yourself without messing up
3. Replace window with professional help

It doesn't make sense to replace the top given the information.