I think that the tip is one of the most important things to look for in a break stick. You want a very hard tip to maximize ball speed on the break, but if you are a league or tournament player, than something like phenolic may not be allowed, as most leagues require a leather tip. You also need to take into consideration what other uses yuou might have for the cue such as will you be jumping with it? Masse? Back up player? Those and others may affect your final selection of weight and tip choice.
One last note is that few if any of the top players are using super heavy cues to break with anymore. The prevailing theory is to go an ounce or two lighter than your main player, and sacrifice a little power for increased ball control.
Dave
Oh, and since its the FS section, I may as well note my inexpensive raffle for charity... I am raffling an action jump/break cue for 2.00 or less for spots... You should check it out...