mcodecuda just showed what this particular carb number sells for in real life. Not advertised asking price.
The “ones that sell for big bucks” are different numbers, harder to find, and/or for more expensive cars. OR they are completely re-plated, re-bushed. Which costs and additional $200+
Save your rebuild kit for something else.
And sell it for $125-$100 without rebuild. That will be a 2.5 to 3 times profit from your $40.