I recently wrote a blog post about the new NAS I built myself and why I didn't choose for a RPI 4. https://jeroenpelgrims.com/diy-nas/
I think it terms of price it won't be much more expensive than an RPI NAS, but you'll get more performance and stability.
If you don't care about power usage and/or connecting stuff through USB you can also buy some older hardware instead.
I recently wrote a blog post about the new NAS I built myself and why I didn't choose for a RPI 4. https://jeroenpelgrims.com/diy-nas/
I think it terms of price it won't be much more expensive than an RPI NAS, but you'll get more performance and stability.
If you don't care about power usage and/or connecting stuff through USB you can also buy some older hardware instead.