The best advice I can give is shop around. Not just for lowest price but also for highest quality. Normally you wont find both quality and low price in the same place.
As an example, lets take a recent repair requiring parts.
My 1995 Toyota Camry had 144,000 miles on it when the radiator started leaking. In addition, the battery was over four years old and needed replacing to make sure the car would remain dependable. Unknown at the time, the alternator was also ready to fry its regulator and needed repair. I ended up replacing the radiator, battery, repairing the alternator, and installing a new timing belt, waterpump, and camshaft oil seal.
Toyota recommends timing belts be changed out every 60,000 miles. Since these really are belts and not chains, the chance of the belt actually breaking is a real possiblity. If this happens when the engine is running at speed, the loss of syncronization could damage pistons and valves.
The waterpump is hidden under the timing belt cover. The camshaft seal is pressed into the block behind its shaft pulley. Since the timing belt cover needs to be removed to replace the timing belt it makes sense to also replace the seal and waterpump at the same time.
I always like to get the parts I need before I start the job. Sometimes I dont use all the parts I get but they can always be taken back or used at some later date. The important thing is that I have what I need to get the car running again because I will be without decent transportation when the car is partially dissasembled.
So I found myself shopping for radiator, waterpump, timing belt, alternator, and oil seal.
I first checked eBay and on-line internet car parts stores to get an idea of prices. New, genuine Toyota waterpumps were price over $200. Genuine toyota timing belt kits were also offered in the over $200 price range. Genuine Toyota alternators were also $200 plus items. I did not bother to check the radiator prices.
Both the alternators and waterpumps were available as remanufactured for about half the cost of genuine Toyota parts. Unfortunately there is no way of knowing what you get with a remanufactured part. You dont know who did the remanuafacturing, where they are located, or to what specifications they were tested.
No, the brand name is not a sure way of finding out because it is quite possible that one faclity rebuilds on contract for multiple brands. Also, there is no way of being sure that the core that was rebuilt was a genuine Toyota core and not some cheap third party knockoff. Third party knockoffs were also available new at prices less than Toyota was asking. Not surprizing, the warrantys on the the rebuilt and cheap knockoffs were measured in months while the genuine Toyota parts had warrantys measured in years.
You can avoid the high cost of genuine parts and still get genuine parts by buying from a salvage yard that salvages from late model, low milage cars. Of course there is no way of knowing where a salvaged part came from. Most likely it was from vehicle similar to the one being repaired but that is about all that can be determined with any degree of certainty. There is a big difference in price. For instance an alternator for my Toyota could be purchased at a salvage yard for as little as $50. I dont live next to a slavage yard so there would probably be anther $10 t0 $20 involved in shipping the part. Then there is the possible delay involved in waiting on its arrival. Sometimes even a $150 savings may not justify the added work and inconvenience involved.
The alternator was finally taken to a local alternator repair shop. The regulator was replaced and the alternator was tested for proper operation. Cost was $70 including tax.
The timing belt, waterpump, and oil seal were purchased from NAPA along with some degreaser and anifreeze. The total for that came to just under $90. The timing belt was one of the long life, high nitrile belts, costing $34. The waterpump was a well known Japaneese brand and cost $32.
A new radiator was priced at $150 at NAPA. We elected to take the radiator to a radiator repair shop. The shop wanted $100 to repair the radiator. One of the tanks was cracked and the repair was non-trivial. They also offered to sell us a new radiator (aluminum) for $100. We settled on the new, aluminum, radiator.
The battery should have been a no-brainer but turned out to be an education in how badly a consumer could be taken. It would have made sense to go back to the place the old battery had been purchased. After all, it only cost $50 and had served well for over four years. Unfortunately that place was no longer in business so we decided to go to the better known Pep Boys.
The Boys had the battery we needed. They had it in two flavors. One at $56 with a one year warranty, and one at $66 with a two year warranty. We figured $10 bucks up front was better than another $56 after 12 months so we loaded up the $66 battery and headed for the checkout counter. After exchanging some information they claimed they needed for the warranty, the final total came to $87. We declined. There had to be other Mexican battery makers that were not as proud of their product.
Turns out we were right. Walmart offered the same battery with two year warranty for $37.99. We got out of there for $50 and a voucher for a $7 refund if we brought the old battery back.
It took two days and $340 to service the car. Low estimate on having the work done at a garage, a qualified garage (not a dealer), was $1800. You can save quite a bit of green by getting your hands dirty. You can also save quite a bit of green by shopping for parts. The parts we used were of Toyota quality. Had we used genuine, new, Toyota parts, the bill for parts alone would have been upwards, of $700.
There is another way to look at this experience. We like to view this experience from the perspective of having saved money. The other perspective is that you can be taken to the cleaners in a significant way if you are not careful.