There's nothing really "budget" about your build, except to the extent that it doesn't include an SSD -- that's the only thing that many non-budget pcs are shipping with these days. It's definitely not needed, but the speed improvement would be noticed. If you got one, you'd want to get one in ADDITION to your 2tb hard drive, not instead of. Might be something worth considering. You could get a 128gb SSD for under $100, and just put the OS files on it -- making sure to install programs on the 2tb drive. Again, not needed, but would be noticed.
As for keyboard and mouse, I'm a bit fan of wireless mice and I wouldn't let any of the corded mouse lovers on this forum convince you to buy a corded mouse

Corded keyboard and cordless mouse (with a long-living and easy to change battery) is the way i would go. Just make sure they have good reviews and you'll be fine.