Thanks for all the ideas, everyone! I received the Rondo Clinic shirt for Christmas and love it. I also have a Rondo jersey and am pretty sure I am going to get one more of the replica jerseys (around $45) of either Garnett, Pierce, or Allen. That is going to be one of my hardest decisions. I have quite a few Celtics books, and I really enjoy them.
I am also interested in possibly purchasing the team trading card set, because I am attending a C's game on March 27 (in Minneapolis) and was hoping to try to get some autographs. A couple friends said if you arrive early enough you can line up to go back into each teams tunnel (I would literally be in heaven!)
Again, I appreciate everyones input. I live in Iowa and there is basically no true Celtics fans out here so I didn't really know what shirts/shorts/hats/etc. were popular and what people liked. I would be satisfied by nearly anything they have on the site!