Kiawah isn't exactly the place to go for a trip that "doesn't cost a fortune". It's upscale and has good restaurants but is in general a very calm and laid back place, so it might not have the type of nightlife you're looking for. BTW, renting a villa rather than staying at the hotel (The Sanctuary) will save you a lot of money.
For the golf, there are 5 resort courses. The Ocean Course is the only one that's truly a world class course, but you'll definitely enjoy the others. The others are all pretty similar in quality (except for maybe oak point which I haven't played but have heard it's probably the weakest). It'd probably order them 1. Ocean Course 2. Turtle Point 3. Cougar Point 4. Osprey Point 5. Oak Point.
It sounds like Pinehurst may make more sense for you guys. Staying at the Pinehurst resort is unfortunately probably even more expensive than Kiawah nowadays, but there are many excellent courses in the area unaffiliated with the resort. Mid Pines, Pine Needles, Tobacco Road, Dormie Club (going private soon, so probably won't be an option for you), Southern Pines, etc. . Rent an Aribnb and play these courses for way cheaper than it would cost to do a package at the Pinehurst resort or at Kiawah.
If nightlife is more of a priority, Myrtle Beach is another option, but the golf won't be the same quality as Kiawah or Pinehurst. Honestly, it's probably not worth traveling from another country just to go to Myrtle Beach lol.