Danny, they are hundreds of beautiful Mickey Mantle autographs on Ebay that are certed by PSA.
Buy one with a PSA or JSA cert.
Every so often, a collector will find an authentic Mantle (with or without a COA) at a great price, but collectors who know autographs (like myself) will scoop them up. Also, high-volume dealers of PSA and JSA certed autographs will also pick them up to flip later.
For someone like yourself, take the time to learn. But if you want something immediately, stick to PSA and JSA.
One of the advantages of eventually knowing autographs is that you can find great deals all of the time.