Where is the best place to get championship memorabilia?!

I'm talking team signed footballs and all that when they release. You can never trust ebay and I don't mind paying a little more to get it directly from the team and be 100 percent sure it's real and authenticated. I know a lot of scalpers are gonna be buying them to resell or study them to fake them, I'm trying to get ahead of the curve here.

Thanks for any info!