Rule of thumb
A quality product will have the makers name and hopefully a serial number on it.
A garbage product will have no identifing markings so you don't know who made it
A pirate aftermarket part will have obvious marks where the original "walbro" "ruXing" "runsruff" was ground out of the moulds that the pirate company bought as scrap metal from the original parts maker .
Now I can write all sorts of BS about how good I am and how much I know and how good the product is and none of it is worth the electriclty used to display it on the screen
The current price of die casting zinc is $ 4.50 Kg and that is a world price so the factory in China that made the carb has to pay that price just for the zinc.
Then it has to be melted, cast, machined & assembled
Finally shipped
Ammozone takes around $ 3 to $ 10 per sale depending upon the volume & weather Ammozone did the warehousing & despatching.
So the vendor gets say $ 15 to $ 8 for it , assuming they are only making a 30% general retail mark up that means it cost them $ 10 to $ 6 delivered & taxed
The factory in China has to be making a profit and even in China that has to be at least 20% or they won't be there next year
So working back that makes them in the order of $ 8 to $ 3.50 at the factory gate cost price, ignoring packaging costs.
So if you think you are going to get a high quality carb for $ 18 then you best get cracking with your letter to Santa Clause because Christmas is coming
If it looks too cheap to be true is usually is not true
Now they could have been surplus sold at a knock down cost price or they could be scrap metal