I do not own, and refuse to buy, a full set of "black tie" garb. I would use such attire at most once every four or five years, and would have to manufacture reason to do that. I'm not likely to go to the trouble to rent formal wear, either--that level of formality is just too artificial for me. In short, if the invitation specifies "black tie," I won't be there. You need not worry about seeing me wearing a tartan tie over my tweed kilt at your precious black tie event.

Remember, gents, that kilts were originally WORK clothing for rural folks, not formal wear. My grandmother taught us to "put your best money in your everyday shoes," meaning buy good quality on what you will wear often. Don't spend money on stuff you won't use.