There are a few places that sell a "modern" kilt jacket like this one I won on eBay:


In particular Freedom Kilts and the Tartan Museum. I haven't received my Harris tweed one from the Tartan Museum yet.

These are more like sport jackets and you can get away with a less traditional look. Most people prefer a tie with a traditional Jacket (Argyll, Crail, or Braemar: that is anything with epaulettes or the shoulder jobbies). There I am less of a Kilt snob than others here and agree with the whatever you feel comfortable with.

But, I would personally wear a tie with the traditional jackets.