Quiet 4" fan

What is the quietest 4" fan for a carbon scrubber for a 2x2 tent?

Trying to keep cost and noise down

I have a grow the exact same size and got te fan in the link below. The only noise I hear from it is the air moving. My 26"x24"x60" cabinet is in my basement and if the furnace is running or i have a dehumidifier running you can't hear it at all. Even when its dead quiet you can barely hear it and thats just the air blowing out the back of my cabinet.

https://www.amazon.com/gp/product/B0027E3Q4Y/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Edit: I forgot to mention I have a large, for the cabinet size, homemade carbon scrubber and it pulls air through that without any struggle. I also used insulate ducting on the back end to remove the noise I did have from the original flex ducting and that noise was just the air vibrating the metal of the ducting at the bend I have in it.
Literally my setup is scrubber attached straight to the fan, the fan, then like 16" of the insulated ducting making almost an s curve to a hole i drilled in the back of my cabinet for the exhaust hole. Honestly could've just went out the side if it weren't for the fact I didn't want my landlord at the tie i built the cabinet to wonder why i had a locked cabinet blowing air out the side of it in the basement lol.

Any of the inline blowers. You can muffle the sound. Wrap the blower with an old blanket. Stick the blower itself in a box with the duct running out the sides. Fill the box with any sound deadening material you have on hand. Old clothes. Foam....

Anything that will insulate the constant 'whoosh' sound. Get inventive and stay cheap at it.