I have not seen an ICD P:R: Connection on eBay in a long time. I like it's small form factor and lack of power supply compared to the 850. I recently bought an Epson FX-980 dot matrix printer just to be able to print using a P:R: Connection. It is funny to hear the dot matrix go to work after all these years. Today's generation have no clue how incredible things like dot matrix printers and modems were in the 80's. I remember buying a 1200 baud Hayes modem and the salesman telling me that 1200 baud is the fastest you will ever be able to go on a phone line. There is always the criticism that Atari lacked expansion slots like the Apple II. It did, but in the end, Atari was way ahead of it's time. The SIO of 1979 is today's USB. You can plug anything in and it knows what it is and can talk to your computer. It was the first "plug and play". Once you bought an 850 or P:R: Connection, your 800 could do what an Apple II could, but the Apple could not say the same. Up until about the end of 2016, you would see P:R: Connections on eBay, but since 2017, I think I've only seen one. They aren't as rare as ICD MIOs, but they are getting scarce. Atari apparently sold a ton of 850s and must have had pallet fulls that they never sold. I had an 850 back in the early 80's, but now the P:R: Connection seems like the best option.