Try also opengameart.org and freesfx.co.uk

Be careful to double check the licenses, for example freesfx requires you to credit them.

Enjoy!

Yes, you can find free SFX but you really need to be careful because often they come with requirements. Your best bet is to hire someone or pay for an a la carte website where you can buy truly royalty free SFX. But that, of course, involves money. If you're willing to spend even just $20 or so, check out Soundrangers.com and SoundDogs.com as well as Pond5.com for some references. 

Hope that helps, 

Nate