Generally speaking I go to two parts stores and shop online for my parts.
I go to Napa for my parts in most cases. I go to Autozone to dump my used oil and on rare occasion I will get a part from them if it it's aft 1 on Saturday or on Sunday, NAPA is closed then.
In a lot of cases Napa doesn't list a part for my 51, so I go online and find it. Usually I shop RA,, Amazon and Ebay to see what the best price is and get it there. Since they all now charge sales tax I look at shipping too. I have found, generally, that Amazon's "free shipping" prices are as much or usually more than RA's shipping added prices. Some times Ebay wins.
Been looking at twin Weber IDA based EFI throttle bodies for a build and Ebay is way cheaper for the same item compared to Amazon.
