I did a little research and found out that were as skeletons and zombies and such give 5 xp each, blazes give 10. Here is a video I found on how to make one.
http://www.youtube.com/watch?v=nrtcJ4c_6oQ
I did not know that. I do know that brayntsang has a blaze spawner set up. Until we get on set up, Ask him to take you there.