I'm not too proud to go "used" if it allows me to get stuff together well ahead of time!
As Jock Scot has pointed out, many Scots wear hand-me-down kilts and accessories, so there's absolutely nothing wrong with "used". In fact, it's in good keeping with Scottish traditions of thriftiness!

If I may ask, what else is involved in "representing Scotland" at this function besides playing the pipes? Are you expected to deliver a speech on Scottish history or culture?