Thanks for posts Fastsavage. My apologies for involving you! and Happy New Year to you, MacNB2 and especially to tsialex!
I have found two local to Melbourne Australia single 4 channel cards, which I think would do the job.
They are:
Cheapest is $Au45 ($US32) - SST-ECM22
SilverStone ECM22 Dual M.2 to PCIe NVMe/SATA Adapter Card
It has a local 1 year warranty. But it doesn't have heat sinks. Its duel, so that is very low cost considering it list Mac OS compatibility.
Secondly there is a local 1 year warranty for the same Silverstone brand, one which has a heat sink included, and importantly, it has flashing LED lights as well (these sell mostly to PCs of course hence the low prices):
2nd Cheapest is $Au49 ($US35) - SilverStone ECM24-ARGB M.2
SilverStone ECM24-ARGB M.2(M Key) NVMe SSD to PCI-E x4 Adaptor Card, Heatsink, Thermal Pad and RGB LED Indicator, Compatibles with M.2 2230, 2242, 2260 and 2280
Also list Mac OS compatible (although says OS 10.13 & 10.14 - I presume later would still work fine as I think the issue is the firmware.
Please note the LED lights - essential for verifying a PC's true power.
Third low cost alternative is a brand we all know - OWC. They have a card that is locally available from Macfixit (who'd ship to NZ too - apologies Fastsavage but you have a good product and that is what matters at the end of the day):
Third Cheapest @ $Au 69 ($US 49): OWC Accelsior 1M2 PCIe NVMe M.2 SSD Card
It comes with a heat sink too. There is a video on installing it, as OWC do often do:
The card:
I have also found the $US 305 HighPoint Technologies SSD7101A-1 card locally to Australia. This issue is that the seller does not list the card's description. However all the visuals show the card's name. I will have to contact the seller, and then perhaps, the seller will change the price. Or I could buy the card and then have a fight if the seller ships a different card to the one his advertisement advertises. I am unsure who is the potential unfair person or should I say - unethical person: myself if I buy knowing the card is under priced - or if the seller is doing something not right. Also I suspect the card is being dropped or discounted soon. Highpoint have said the SSD7101A-1 is being replaced soon, by a better card.
Now I may be all mixed up with all this. I have only got this information by reading Highpoint's web site, and the Web. To get reliable information, I should have spoken to Highpoint themselves.
So please tell me to what extent I may be wrong!
For a while I thought the new card had been out for a while - but it seems my information may be current, and that the new card hasn't yet landed. But Highpoint has also said they will continue to sell the SSD7101A-1 card - hence I presume, it will fall in price. I am pretty sure I saw the replacement cards price as being similarly priced to the current SSD7101A-1 price. If so SSD7101A-1 would fall in price, or, Highpoint would withdraw it. They have previously revised the same card I think.
Mostly the new card's price is not listed. Also, some sites now list the SSD7101A-1 as no longer being available. SSD7101A-1 does a great job, but the next version will be better (due to better heat characteristics with newer hotter drive cards, and also it will work faster in some computers). But I doubt it would perform better in a Mac, especially in a slow old bus 5,1.
As listed I think in the first page, Highpoint sell a number of cards. Those that can take 8 NVME drive (cards) on the one cards, I will not mention as they cost a lot more and are beyond reason for most of us here. IF NVME cards were much cheaper in lower capacity, such 8 slot cards might be worthwhile. But my costings show 2TB as being the better value per TB. However, RAID increases speed ... and can increase security. Sheesh ...
Highpoint:
An 8 channel card that holds two cards only. SSD7202 – PCIe 3.0 x8 2-Port M.2 NVMe RAID AIC RAID - It has a RAID controller on the card - cost here is about $Au 470 - $US 333
Then there is the Rocket 1101 4X M.2 PCIe Gen3 x16 NVMe - it costs $Au505 - $US 359
It supports up to 4 cards, is 16 channel, but you have to use the computer for a sotware RAID, rather than its own controller.
I should say too - in early 1994, I was putting in an NT servers as the core for a Mac environments along with image setter, scanners, Quark Xpress, Photoshop (I think version 1.4 and it wasn't owned by Adobe back then) etc. (I was digitising newspaper workflows) - and I used a RAID card back then in a Windows NT server computer ( a fraction of the cost of Unix servers and they were easy for staff to operate). NT was brand new back then (late 1993 it came available). and it supported Mac's low speed standard wired network. Such a card cost well over $Au3,000 back then. In today's money, such a card would cost maybe $15,000. And of course it was very slow ... today, Highpoint charges about $US 70 for their RAID controller hardware chip on the card.
Finally there is the SSD7101A-1 which costs normally around $Au 600 or $US 425. It includes the RAID controller processing unit, is 16 channel and supports 4 cards.