Adaptec ASR-8405 12Gbps SAS controller cards available for $35 as of 04-29-21 E-Bay.
For those that are using an older SAS/RAID controllers such as the PERC series and looking for a cheap upgrade path, there are adaptec ASR-8405 12Gbps drive controllers currently going for $35 on Ebay. The controller does work with individual, RAID or drive array setups and also backwards compatible with SATA HDD and SSDs at 6Gbps and can handle SAS HDD and SSDs up to 12Gbps. If you're using a Dell T7600 you will need to get a Dell Precision T7910 wiring harness kit (recommended) and swap pins 9 and 12 on both 24 pin power connectors if you want to use this card with that kind of rig. Those using a Precision T3500, T5500, or T7500 (for example) just need to get a SFF-8643 to SFF-8482 (4 way) replacement cable. I've personally been using the card for months with no issues and with different drive types.
For those curious my current setup using this controller includes:
Dell Precision T7600 with modded Dell Precision T7910 drive harness
[storage drive] HGST UltraStar SAS 8TB 7200RPM SAS-HDD 12Gbps Model HUH728080AL5200
[boot drive] Toshiba 200GB 2.5" SAS-SSD 12Gbps SAS-SSD Model PX02SMF020
Forgot to mention to everyone that this controller does run hot so give it plenty of ventilation (I used a dell CPU fan pressed between the upper housing and the RAM cooling shield mounted in the upper PCIe slots).
If you're willing to spend an extra $25 (A bit pricey IMHO for what it is). Mouser.com have the offical adaptec fan kits for this controller here.
The card do work out of the box with current versions of Windows and current Linux distros, but drivers for older versions of both can be found here. Monitoring software for the controller card for Windows and Linux can also be found there.