It is imperative that you always do your own research against any mechanic telling you what you need. Factory certified mechanics and dealer service are also generally bad sources for repairs. Some stories:

Took a 2002 Mountaineer to the dealer due to an engine light. They diagnosed an egr valve failure and a sensor failure at the muffler. Quoted price: $860.00, and for some unknown reason, said that it wasn't covered under the extended polution warranty (as opposed to the 5/50 that came with the car). As an explanation for the price, the dealer also said that they had to remove a goodly part of the top of the engine to get to the egr valve.

Some quick research on the net told me that a bad egr valve would throw a code for the sensor at the muffler, and that you replace the egr valve first. Replacement cost of the egr valve at Auto Zone: $69. If you buy the part from them they'll also flash your codes for free (vs. up to $90 diagnostic at dealer). The part was an in-line vacuum piece at the top of the engine with two vacuum lines and one elec. connection. Total time was two minutes. The dealer just plain lied.

I reported this gouging to Ford, and was told that dealers could charge whatever they want. I followed-up with a letter explaining that this was not charging whatever they want, but rather, due to the explanation by the dealer, this was outright fraud. I also noted that when people find out that their dealers are crooks, their repeat business would suffer. Ford did not seem to care.

On another note, I got a quote of almost $1000 to change a heater control valve on a Catera from a dealer. He showed me where the part was and explained that he had to remove the plenum to get to it. Looked like this was correct.

Again did my own research. The U.S. practice was, indeed, to remove the plenum to get to the $60.00 part. The problem was that when they reengineered the American manual for this Opel Omega, GM's engineers did not know of a simple access panel specifically designed to reach this part under the plastic vent covering at the cowl. Forty-five minutes and $60.00 later it was all fixed. In this case I showed the procedure to the Cadillac service department, and they thanked me for the saved knuckles. I don't know if they lowered the price though.

Last story. At 100,000 miles I decided, as preventative maintenance, to change out all the rubber on the cooling system on an XJS I owned. Jaguar's price for the pieces was $526.00 with some single hoses as much as $149.00. Their charge for doing the same work was $1600.00 with parts.

Took off the parts, went to Auto Zone, and they let me into their back where the hose wall was. Matched up the pieces and found everything. They weren't Jaguar parts, and in some instances the match was only in the middle of some other manufacturer's twisted cooling hose. It's not that hard to cut out the matching piece. Final cost: Parts: $72, Labor: 2.5 hrs.

Also on the XJS, the cats went bad. System had two cats and two pre-cats. Dealer cost to replace: $4199. Local independent muffler shop fabricated a full system from the headers back, deleted the pre-cats, put on two high-flow after-market cats for a Camaro and two new and better sounding mufflers as well. Total cost out the door: $650. Incidentally, it smogged better than the stock system, and felt like I picked up a few HP as well.

I feel for the people that don't know the difference between SAE and metric, and are at the mercy of these businesses. Knowledge is king, and its gratifying to hear that you did not line the pockets of yet another opportunist in this pervasive charade known as auto repair.