Yep, a big difference between cleaning a window and replacing a window. Any owner that thinks he can make and fit parts to a certified aircraft would have to have rocks in his head.
It makes you wonder about the knowledge and skills level of some of these blokes. As for the hangar elves, well they are the ones that just ruin it for those that are trying to do things correctly.
Fortunately there are not many about but they do exist.
The owner should have the courtesy to keep his maintainer abreast with any maintenance activity and preferably at the earliest possible stage. I would think that most LAME's would be obliging and come up with some good suggestions that keep the costs down.
There are some great products about these days that would clean-up the transparencies but replacement is often the best option.
I see many aircraft logbooks and it is always a shame to encounter a machine with unrecorded maintenance in the logs.
It ruins the aircraft and generally costs well over the top to get sorted.
They would be the same guys that complain about the cost of their maintenance.
For those owners that want accurate logs then put it in the log yourself !
If you aren't prepared to certify for your own work then at least have the courtesy to ring the LAME for advice.
I think a number of people would have their noses out of joint if the aircraft just sprouted a set of new windows overnight. I am sure it would look much nicer however..
Asking here for cleaning products and methods is a good start. There will be owners, and pilots, that have botched a simple cleaning job.