Disagree. There is a lot of affordable Neurofeedback hardware/software out there. It is BCI hardware that is lacking. With BCI applications/research you want as many channels as possible, and that makes it expensive. In fact, just a decent set of cables and electrodes will cost a few hundred $US, which is more than most people will want to pay. Then we haven't even spent anything on the amplifier.
For Neurofeedback you need two channels only and the market for these devices is so (over) crowded that I stopped further development of my own 2-channel systems a few years ago.
NFB and BCI are 1000 miles apart. I don't do either and have spend my time more on the hardware development side. However, I must have spent 200+ hours following Pete van Deusen's BrainTrainer yahoo group that only deals with NFB, so although no hands-on experience, I know a thing or two about NFB applications. I have discussed this subject in some detail on the OpenVibe forums.
In a nut-shell, if you want to do NFB, you get a decent 2 channel amplifier and BioExplorer. Doing anything else will be wasting your time and money. Of course you could use openBCI hardware, or some other BCI hardware, but it would be silly. If I want to plant a tree, I would use a spade to dig the hole. Using a back-axle digger or a spoon would give less favorable outcomes, although in theory, you could use said devices as well.
To learn NFB protocols, THAT is the hard part. Yes, you could use BrainBay, OpenVibe or any other software, but then you would need to implement training protocols from scratch on these software systems. With BE you have a huge community and you have access to training modules, etc. The only other practical NFB software is BioEra, technically more powerful and advanced, but it is much more challenging to use and learn. More problematic is the fact that there is not a big community to draw on.
I would say that 99% of NFB is done with 2-channel bipolar systems. I have seen here or there a person having reported that he has created a 4-channel protocol.