$120k for a customized system that's central to your entire business doesn't sound that expensive really. Can you make your own? Sure, but the devil's in the details. Complex systems are always more difficult to make reliable than you think. If it's down and you're losing business, who do you call? Yourself. Besides being a bowling alley owner, now you're a tech startup entrepreneur with one customer. It might end up fine, or you might end up with a whole new set of headaches.