You'll see everything from Velcro to snaps to webbing/plastic buckles and beyond! If you want to stay more traditional, you can make straps from matching fabric instead of leather -- there's a nice picture of that in the XKilts instruction manual. If you haven't taken a look at it, be sure to -- it's far from traditional construction but a great way to cut your teeth on kilt-making.

I think this is the most current link:
http://cmgm.stanford.edu/~ahebert/Xk...t2ndedRevK.pdf