Get the kit.

Yes, buy the matched 2x8GB kit over two separate sticks. The price difference is usually tiny—like $5-10—and the kit guarantees the sticks are identical and tested to work together in dual channel. Separate sticks might be from different batches, have slightly different timings, or just not play nice. That can mean no dual channel at all, which kills memory performance. For the small premium, it’s not worth the headache.