Even an inexpensive cue dedicated as a break cue is a huge benefit.
If you're looking for a house cue to break with, every time you go to the poolhall, what are the odds you'll use the exact same one ? Sure, you may find one that the weight is the same, but the tip(s), taper(s), straightness, and so on will be marginally different.
With your own break cue, you can 'become one with the cue' and not need to deal with inconsistencies between cues, but you can also learn what works and what doesn't in regards to your break shot.
Having your own break cue will eliminate a variable that can affect your mastering of the game.