ZapSplat provides free sound effects that can be used in any non-commercial, commercial and broadcast production in exchange of attribution. Thanks for putting this up, very useful. Music and sound effects play a significant role in giving a game a character of its own. Unity asset store has a collection of free sound FX, music and ambient sounds. Free Resources , Game Development. Incompetech has royalty free music tracks available under Creative Commons attribution license.
Slot Machine Sound
Otherwise, Pure GCE gets my vote. Good product except the product isn't the best. I've tried a few different brands and this isn't the worst but it's not the best.