How do you determine the value of 2008 autographed Golf memorabilia such as caps or pin flags?

You could take it to a professional who studies autographs and get him to confirm that it is the genuine article.

Stan Musial Autograph values. A Stan Musial signed baseball is worth about $60.-$100. In general photo's will sell at about 40% -60% the value of a signed baseball, cut signatures, and index cards...

Some are 7 feet, some are 8 feet. If the green is over a hill I have seen them 9-10 feet.

If accompanied by a certificate of authenticity quite a lot. They are moderately rare, but hard to put an exact value on. You should try a sports memoribilia auction at a reputable auction house. You...

The "Pin" is the flag stick onto which the flag is attached.