“Much lower” is still quite expensive compared to a mainstream platform: the absolute minimum if you already had all the other pieces would be the motherboard and CPU bundle for $2,133.77:
https://secure.raptorcs.com/content/BK1B01/intro.htmlThat’s 8 cores, which since Power9 has SMT4 means 32 threads. The 4 core CPU bundle is a bit cheaper but when you add the 2u CPU cooler its price gets very close, so it’s not worth it unless your computer case is too narrow for the 3u (≃15 cm clearance, https://en.wikipedia.org/wiki/Rack_unit) cooler included with the 8 core CPU.
It won’t run AmigaOS unless on an emulator[1], and then you’re better off with AMD/Intel: you would lose more performance in emulating the CPU, but you would get more raw performance for your money anyway.
[1] https://forums.raptorcs.com/index.php/topic,75.0.html
If you want to run AmigaOS software natively on PowerPC your best option is a PPC Mac running MorphOS. It even runs on the PowerBook G4: https://ddg.co/?q=morphos+powerbook+g4
Or if a well-integrated emulator suits you better, take a look at AmiKit: https://www.amikit.amiga.sk/
I don’t think that this CPU would be a net advantage for those use cases. I did use Amiga computers even as Commodore went bust, hanging on, but the approach I’m going for now is FPGA implementations:
https://misterfpga.org/
http://www.apollo-core.com/index.htm?page=preorder
I’m in the waiting list for Vampire4 Standalone, but for now I’ve got a MiSTeR.
So no, don’t buy a Power9 hoping to run AmigaOS on it any better than on a mainstream PC.
P.S.: the $1310.99 price mentioned by aww_dang must be from a few months ago, the current price displayed in Raptor’s website is $1732.07. Prices went up due to the current COVID-19-induced crisis, which also made Raptor cancel their upcoming Condor platform (ATX Power9 but LaGrange-based: twice the memory bandwidth): https://www.talospace.com/2020/07/condor-cancelled.html
P.S.#2: for those in Europe, Vikings (https://vikings.net/) has been trying for a while to offer them here and they might be able do so it soon: https://www.talospace.com/2020/08/vikings-upcoming-openpower...
P.S.#3: used BlackBird with 8C Power9 for sale in Germany: https://forums.raptorcs.com/index.php/topic,153.0.html