False.
It's going to cost you at least 60 dollars just for the Raspberry Pi, power supply, HDMI cable and case. You still need the SD card, and controllers.
That's if you don't want anything that is appealing to buyers, like an attractive retro case, lighting, or even a power button.
There's a reason why those NES classics sold like crazy. The price point was perfect for what you got. Had the supply not been so crappy, I would have gotten one as well, and I say that as a raspberry pi user who set up retropi in a Sega Genesis USB hub case.
While I don't disagree with your latter sentiment, conflating in the price of a power supply and HDMI cable is kinda silly. I'd hazard a guess most folks have a spare micro-USB chargers / cables laying around, ditto for a spare HDMI cable. I have a bag full of MicroUSB chargers, and it doesn't take too much digging to find one pushing 1A-2A.
Realistically you're looking at like $40 for a Pi and a case, the rest most folks probably have laying around. It's not like NES roms take much space, you could probably use a 1 GB SD card from the 2000s if doing NES emulation is your only goal.
It's like when people were including the price of the Xbox 360 official wireless adapter in the price of the console back in the day.
The real barrier is software, it takes a bit to configure a controller, figure out how to do stuff, etc. It took me half an hour to figure out how to scrape F-zero (didn't realize a current retropie image would need a bunch of package updates, nor is the sselph scraper seen in the UI).
I agree though that people wanted them for the nostalgia factor - that's why I got mine! I've had a full running Hyperspin setup, and I'm working on a Sega Genesis USB Retropie myself right now, but the NES classic is awesome cool.