Is more expensive better? Is even more expensive not even as good?

Still working on my lean mixture. It's a good excuse to buy tools, even
if the tools cost more than taking it to a shop. ;-)

But I don't want to waste money either.

Which to buy:

https://www.amazon.com/Carburetor-Va...SFQ/ref=sr_1_1
Costs $17.50 and looks just like

https://www.amazon.com/8milelake-Vac...NAK/ref=sr_1_8
which costs $25.99


When two things look exactly the same but one is 49% more expensive, are
they the same, or is the more expensive one somehow better?

OTOH, if they are the same, how can there be such a big difference in
price?**

Then there is
https://www.amazon.com/Bosch-FIX-780...CL/ref=sr_1_27
which is a little more money $31.31 and looks A LOT nicer and has a
famous brand name.

yet it has fewer attachements, just 3 (counting the one already in the
hose) instead of 6. Why would anyone buy it and then have to look for
connectors separately?

(In addition, the EVAC service port for this car is hidden under the
air-cleaner box, and since I only have one car, I don't want to take it
apart to see what the port looks like, then put the car back together
until I get the vacuum tester.



**Yes, I've seen that before. 3 or 4 months ago bought a 24" smart LG
TV from Abt, in Chicago, and it was about 200 when other mail-order
stores wanted $320 for the exact same model. I'm still trying to figure
out how they can be so much cheaper, why I never heard of them before
(even though I lived in Chicago for 6 years), and if I should look into
buying everything from them.

I thought that even without illegal price fixing, prices tended to be
about the same, and certainly not 60% of another store's price



(I didn't even thing Abt was their name. I thought it was an
abbreviation of something. But it turns out there are 13 famous people
in wikip with the family name Abt! Not to mention the non-famous
people.)