My experience from running two nodes now for 2 years, one I bought pre built and the second I built myself on a reused computer.
  • The cost is in obtaining the hardware and is realistic to spend from $200-$400 USD for this, depending on what you go for.
  • Bitcoin Core is FOSS, so there's no expense at all to access this.
  • I have had no cost in upgrading or maintenance. Electricity costs of running these small servers at my home have not been noticeable.
  • There is knowledge required to keep running and maintaining, especially if you're not using an out of the box node. But this is the trade off for privacy and not relying on a third party to confirm your balance. That's what I've found anyway.