I am looking for something around 400 watts that is durable, actively cooled (120mm fan) but quiet, and a good bang for the buck.
The Corsair PSUs made by Seasonic fit that bill well for a decent price and good quality with generally strong efficiency and smooth loading.
Is there another brand/model you would recommend since it seems none of the major e-tailers sell that model anymore?
Corsair stopped making/branding the vx450w about 9 months ago. I do not know why the ads for the power supply are still appearing here on SPCR. Perhaps the poor revenue performance of the SPCR site has something to do with this type of neglect.
If you still want the Corsair name on your power supply, you have 2 choices. You can go with the new "builder" series, but they use a louder fan and are built by CWT. You can also pay double the amount of money to get the TX750 V2.
If you are willing to give up the Corsair name, you can buy a low-end Seasonic. The down side is that Seasonic does not have the same high standard of quality control and product consistency that Corsair imposed.
Seasonic makes the "S12II" power supplies in 6 sizes, from 380 watts up to 629 watts. They are not too expensive, but they are not as cheap as the vx450w was.
I bought three VX450Ws when it became clear that nothing was going to replace them in the Corsair product line.