I moved your post to the Casual Games forum because there is where we play and discuss Big Fish games.
You can buy games from Big Fish without being a club member.
If it's a standard game and not a Collector's Edition, you will pay 6.99 if you are a Game Club member and 9.99 if you are not.
They also have plenty of sales where non-members and members alike can buy the games with a greater discount - you just have to watch for them.
The first time you get a game from them and you have the game in your shopping cart and are checking out - just make sure that you uncheck the box saying that you want to join the Game Club, if you do not wish to become a member.