i wanna build my gaming PC for the first time triqyno (this is my email if you wann a advice me more) is you good with computerz ? and tell me why
You can try eBay or Craigslist, but I would be wary of used parts.
This is pretty much the best/easiest single site for getting parts. The reviews there tell you the "real deal" with anything you find, so even beginners can tell if its cheap crap, or impossible to use, or randomly incompatible with things, etc.
The prices at newegg are (usually) competitive. But even if you find the same part somewhere else cheaper, newegg was worth the visit to read the reviews of it.
Newegg also has a pretty good return policy. If it doesn't work you can return it pretty easily. If you made a mistake and accidentally bought a wrong/incompatible part, you usually have to pay 15% of the part even if you return it, but that's a LOT better than not being able to return it at all.
I have also bought stuff from Ebuyer before but I always end up with hassle from them so I wouldn't recommend them.