I don't think there are many autograph collectors on this board. For info on Oz, try rebelscum. I can tell you that he does sign through the mail sometimes and other times his assistant signs for him. Good luck.
K9 is a very reputable guy. I will be sending my multi poster to him for a few hard to get autographs however I don't believe oz just signs the autograph, he personalises everything so it would have your name on. Don't know if that would spoil what you are going for.
I'm trying to get the gg mini busts signed so far I have 7 done but the others are very hard to get, a frank oz SIG would look cool on my Yoda v1 but if I sent the bust how would I know he signed it himself or someone else done it? Because does he go to conventions?