One lower cost alternative, if you can find one, is to look for a used PC3 but the older serial version.
I sold the one I removed from my 919, on this forum, for I believe $50.
There is a lot less support than for the USB PC, but can still find some maps for it out there. The maps are a different format than the USB PC3.
If it does not come with a cable you will also need to purchase a cable. Some of the aftermarket cables that will plug into it will not transfer the data, so will need to get one that is data compatible with the PC3.
Link below is the thread of the gentleman that purchased the serial PC from me, and his process of getting it installed and mapped.
Post #15 has pics attached that show a potential map to use, can manually enter the data once the PC3 is installed and connected to your computer.
There are other maps out there that you also may be able to access by making connections with the owners of the maps.
I tried the link, but it did not go to a specific thread or post at my end.
Can you please check at your end?
I'll add a bit more to your info:
Any PCIIIusb map in .djm format can be manually created as a PC3 serial port map in .map format.
One just needs the PC3 era software and it's still available from DynoJet, but on a request basis - it's no longer on the website as a ready download.
Any serial port patch cable will work.
BUT if your computer does not have a serial port, one needs a serial port replicator that patches from your computer's usb port.
The serial port replicators are what can too easily cause all the grief.
Not all replicators can be made to work.
DynoJet used to recommend a certain Belkin device which had been proofed.
At least a couple of WTers got their replicators to work, sometimes with some difficulties in terms of getting the correct driver installed.
For sure, have the correct driver installed is crucial.
The serial port PC3 is indeed still a valid solution, and if one can be found inexpensively and a new PCIIIusb can't be justified for whatever reason, then why not ? !