My goto is usually rock auto. Other places can be cheaper but nowhere else has everything in on place. If I need something quickly then I just go to my local parts shop.

Varies between Autozone, FCPEuro, Amazon, Ebay and the junkyard. Saved quite a bit with junkyard parts.

For most stuff like brake pads, wipers, or bulbs I have used Autozone or O’Reilly, not really picky about either. When I needed the occasional expensive thing like batteries or an alternator I would check prices first and pick the one that was lower for the one I wanted.

This was mostly due to needing the thing right away, so I’m paying a little more for convenience.

I also used LKQ a couple times over a decade ago for junkyard parts like a headlight housing that was damaged.

Haven’t had to do the expensive stuff for quite a few years, just wipers and the occasional brake pads.

I usually see if I can get it from Amazon since we already have Prime. Rock Auto is typically cheaper on the actual part price, but the shipping almost always puts it over Amazon’s price for me. I use Rock Auto to confirm part numbers though, as it’s easier to see a big list of them than the Amazon page giant results mixed in with their “recommendations.”

OEM or NAPA. They’re the only ones that source OEM quality. Everyone else has lesser grades. Even RockAuto (who is amazing for getting part numbers) has issues with quality from time to time.

I’m no mechanic, but I can do brakes. I found the best deal on Rock Auto the last time I did my own.

eBay if I can wait a few days, otherwise O’Reilly’s.

Halfords

Worldpac (no longer owned by AdvanceAuto Parts btw)

If it’s an OEM part that I need, I usually use the car manufacturer’s parts catalog to find a part number. Then I enter that part number in a web browser, and browse through whatever comes up to find the lowest price from a trustworthy source (usually a car dealer online somewhere that sells/ships parts and has an online store, but sometimes eBay, Amazon, etc.)

Aftermarket parts get a little more complicated because it depends entirely on what kind of part you’re looking for.