Running a Bitcoin node requires hardware with at least 2GB RAM, 250GB storage, and reliable internet, with recommended hardware having 4GB RAM and more storage.
Bitcoin Core client software is necessary for validation, mining, and communication, with regular updates required for bug fixes and security.
Costs associated with running a Bitcoin node include electricity usage, hardware upgrades, and maintenance fees, with estimated monthly costs ranging from $10 to $20.
Running a Bitcoin node contributes to the strength and security of the network, offers more control over privacy and transactions, and can potentially earn small transaction fees and demand for nodes, but requires technical knowledge and ongoing maintenance.
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.