No limit. If I'm having fun and things get expensive, whatever I can afford it. Vast majority of dates don't end up being expensive, so if it does happen more than likely you're having a good time and the night is extending. For instance most expensive date I've had...we went out to eat and had multiple drinks for lunch. By the time we were finished the bill was $200 or so (including tip). Left the restaurant and decided to walk around instead of driving for obvious reasons. Ended up going to a random ass jazz club, drinking wine, and relaxing listening to music. That was about $50 total. Stumbled out the jazz club and headed to play Top Golf, spent around $60. After that we walked around...chilled at the park (free), then went to see a movie for about $20. By that time it was 9PM so we went to a pizza joint for a quick dinner (around $40 total) and then went BACK to the jazz club for another $60.
Had a blast man.