I've had the Supermicro fans on my alerts for a while and Amazon seems to be the cheapest at $20 w prime usually. I stumbled across just the fans, without the case, which are a drop in for most of the chassis and only a slight modification on others.
Seller accepted my $6 BO.
Genuine SuperMicro FAN-0074L4 4-Pin Hot Swap Fan San Ace 80 9G0812P1F03 6558051422301 | eBay
Seller accepted my $6 BO.
Genuine SuperMicro FAN-0074L4 4-Pin Hot Swap Fan San Ace 80 9G0812P1F03 6558051422301 | eBay