as a knight I think you can join this tournament if you are invited and Purple said he sent you an invite so it should be joinable right?
Maybe someone can offer to upgrade you to a rook :)

Purple: eek, I didnt think of that
wouldn't it then be wiser to save this tourney up for when ALL the top players are able to play in it.
Or maybe someone could donate a membership to him? I wont because I dont really know him and I have given far too many memberships away in the past but maybe someone who knows him can pop him a 6 month knight membership or something. It's only 10 bucks.
AD hasn't paid for a membership in a while, maybe he is feeling generous?

Purple: This has the makings of being a great tourney Purple.
Also, if any top players refuse, you would have to consider the possibility that they are too scared to lose against other quality opponents

Isn't Black/Red suppose to move first in checkers?