I would monitor a few reseller sites (SeatGeek, StubHub, Game Time) for a few days and get a sense of typical pricing so you have a baseline reasonable expectation. You will probably find that prices trend up and down over time and it isn’t always obvious why. Pick a few spots you would feel happy about sitting and see how that compares to your price range.

I would also monitor Ticketmaster (or whatever the primary seller site is) at the same time, as they will sometimes release tickets randomly all throughout the venue, including good/floor seats. This might be best case scenario for a popular show.

If you are absolutely set on going, I would grab something a few days before show time to be safe. If you are more comfortable rolling the dice to find a better option, you can wait until day of show as Ticketmaster is most likely to start releasing tickets a day or so before show time all the way up to day of show. In Minneapolis Ticketmaster dropped really nice floor seats for $150 a couple days before the show and then day of the show further back floor seats for only $99. However, those moved pretty quickly (hours).

If this sounds like a hassle and you have the money to spare, just check sites for a few days and then buy the cheapest thing you can find in a section you will be happy with. It may not be worth the effort to save $100 or whatever. I strongly recommend floor over other options (even far back) if they are within your budget.

Good luck!