Storage expansion for my server

Any ideas to expand the amount of storage my server can hold
(IBM X3550 m3 7944)
currently, there are two unused pcie 16x servers (PCIe 2.0) slots, one full withd, the second low profile.
Currently I have two of these systems, one of which I am most likely going to equip to server as a storage server.
Those systems both have dual Xeon E5506 CPUs
And I have a combined 64gb of DDR3 ECC ram for both of them

Althought the pcie sata / nvme expansion card/s could be an option, but the chassis is a 1U server (rack mounted) and cannot fit those drives internally
The problem is that I would prefer not to buy large quantity of NVMe drives, since my use case (steam caching, backup storage) does not really benefit from them
and the server has only 2 gigabit NICs, and I don’t really see the need for more
Any ideas

That era of server likely shipped with 1.2TB SAS drives as a max HDD factory option. Those can be had cheap used on eBay but if you need more performance, you might be able to get away with more modern 2TB SSDs which would be much more reasonable than going for NvME.

If I were you, I would save the expansion slots for future use. You never know what you might want in the future. For example, you could pop in a single slot GPU for transcoding media streams or even if you wanted to pass it through to a VM so you have your own cloud desktop and Steam link server.

If you can get an HBA with external ports, you can externally address SATA/SAS enclosures of any size and volume if that’s a direction you want to go. PCIe 2.0 is rather old, but 6Gbit SATA/SAS HBAs like LSI 9200 series could make this fly.

Yeah, I can understand that
I might go with those SSDs, althought the price of those is still quite high still.
And I really would prefer not to buy used, since I don’t know when those drives are going to fail, although the plan would be to go with the least expensive thing I can.

For some context shipped with a couple of 146gb SAS 10K drives…
And one of those has already died.
I’ll try to check, if any local retailers have any enclosures
Update, there might be a couple of options (Chieftec SAS/SATA Backplane 2x5.25" for 3 S-ATA/SAS HDD / 2.5" SATA USB A -kotelot / CBP-2131SAS / - kaikki mitä tarvitset)
(ICY BOX IB-RD3621U3 2 x Total Bays DAS Storage System - Desktop - 2 x HDD Supported - 2 x SSD Supported - Serial ATA/600 Controller0, 1, Concatenation - 2 x 3.5" Bay / 3.5" SATA USB-A Kiintolevykotelot / IB-RD3621U3 / - kaikki mitä tarvitset)
But still, the amount of availlable options seems quite low
I guess I’ll keep looking for something.
And since there really aren’t that many options to buy NAS/server drives , the only ones availlable for reasonable prices are “compute drives”
And for context, there are SAS-drives availlable as well
But for the 135e for a 1TB SAS HDD, it does not really make sense either, since
I could get a Crusial MX500 for 106e