Industrial Strength Disc Polishing

I have tried a couple of Disc Doctor type devices and they all seem overpriced and mediocre in their performance. In fact, one or two discs where I gave the full treatment and polish never worked again - which was even worse than they were when I tried to polish out a few scratches.

By comparison, my local Game Stop store will take just about any disc you give them on trade, and they only deduct a buck or two to polish out the scratches.

Similarly, the local public library also has a machine which apparently keeps all of their CDs and DVDs playing.

In addition, you can bring in your own discs for treatment, but here too they charge a buck or two which I am sure will pay for at least one librarian over the course of a year if anyone uses it.

Therefore, could anyone please post advice, links, or their experience using a high quality disc polishing machine?

If these are not too expensive, it seems it would be a reasonably investment for anyone who had a big collection of music and movies.