Did roughly a 3.14hr drive; a day trip to NB Caverns on a Wed. The overall experience there was great. Booked both a Twisted Trails and the Discovery tour online, total cost for 3 adults, approx $180. Online, the price for the cave was $26.25x3, but at the gate, it was approx $50. The Twisted Trails cost: $26.99x3. If you're military, try ITT center, it might be better. On their FAQ's pg, it states there's a 10% military discount (at the gate only not online), but the online price is, obviously, way better. Also, if you're visiting San Antonio & and you're doing the Rio San Antonio River Cruises, they have discounted deals for the Caverns, too. Not sure how good they are, but might be worth a try if you're in the area.
Had loads of fun a Ben, our cave tour guide was great and knowledge. The food prices were set to be expected. Bonus, they serve canned beer and wine. And you have to try their lemonade, it was fantastic and refreshing. Spent about 40 bucks for 2 beers, 1 wine, bag of popcorn, 3 lemonades. I know, a bit pricey but when on holiday... Hope this helps, you can really spend a good day there full of activities.