Getting good music is either difficult (unless you're a musician), or expensive. Here are some links that may provide good music at no cost:
Create with Mixcraft (can use electric guitar - plug in and use audio track - it behaves like a mircrophone) Can also install VST plugins
MobyGratis - free instrumental music for creators - OUTSTANDING!
Incompetech - Royalty Free Music by Kevin Mcleod - OUTSTANDING!
Free Music Archive - The Free Music Archive offers free downloads Under Creative Commons and other licenses.
Browser based music creation:
Looperman (thousands of free audio loops - account required - can be used inside of Mixcraft!)
youtube music (free for video use when stated)
ccmixter (creative commons)
Public Domain music (wikipedia - lots of free music - mostly classical)
opsound.org (open source music) (free)
Open Source audio (free)
Free Stock Music (account required)
Creative Commons - Music (some free)
http://magnatune.com/ Interesting model where musicians license directly (prices range - $25 per tune)
SoundCloud - most music is not free, but there is usually contact information for the artists
Soundscrate - some free content
Sound effects:
youtube sound effects (free for film use when stated)
Stock Footage:
footagecrate.com (some free elements)
Da Vinci Resolve - sound channels