PowerPC :: Charges Most To Repair Powerbooks?

I know it's a strange questions but my mother's powerbook G4 1.5ghz just suffered from the infamous lower ram slot failure and does not fall within the warranty extension program. However, she has VISA performance guarantee and if the repair is going to cost too much, they will most likely offer to replace the computer with a new equivalent one.

This particular issue, apparently, is not really fixable and people who have their logic boards replaced often experience the same problem again later down the road. Since VISA has a no lemon policy and will replace automatically after three repairs, I figure it's better to save my mother the considerable hassle of having to send it in on multiple occasions...

So: I'm I want to find the most expensive authorized apple repair shop. Any 'good' suggestions?