Maybe I'll accidentally knock a statue into your apartment wall, forming a hole that I will drunkenly vow to pay for. Maybe you'll Venmo me for the wall repair four months later. To factor these (and many, many other) variable costs into my lifetime average, let's add a $12 surcharge to each date. That should control for any and all plates of appetizers, concerts, and lottery tickets. That makes my average $56 per date.
The magic number: $56 per date
I don't think that $56 for a night out is that expensive, but it's not insignificant either. It's enough to make me stay away from dates I don't genuinely want to go on. That's important. Ultimately, an expensive date here or there won't ruin my average in the long run, but that's mostly because I've been on cheap ones in parks and coffee shops, too. If I've learned anything over the course of my 75 dates, it's that the cost has little bearing on the quality.
If a date is going well, you're going to end up spending more just because it's less likely to end soon. On the flip side, even a cheap, bad date costs your time. I've been on plenty of $35 dates for which I want a refund. They say you can't put a price on love, but in the meantime, you can at least figure out how much you've spent looking for it.