The difference between a traditional 8-yard (give or take a yard) and a 4-yard kilt (again, give or take) is going to be the number of pleats and/or the depth of the pleats, all determined by the size of that particular tartan's sett, or pattern.

As if that didn't confuse you, I'll continue. With a fuller kilt, you'll notice more swing as you walk, and that's always considered a good thing. However, a kilt with more material can also be warmer, something to consider if the summers get hot (you didn't mention where in Australia you are). However, I still wear my 8-yard wool kilt in the dead of summer where I live, and it gets up to 100°F (37°C) with 90% humidity here.

As Graham mentioned, you can get cheaper kilts if you purchase in poly/viscose instead of wool. The feel is slightly different, but the maintenance is much easier (throw it in the washer when it gets dirty!) and it's about half the price of a comparable wool kilt. There are many vendors to choose from, but Bear Kilts and USA Kilts are two popular vendors that many on this board can vouch for.

Fifteen is a great age for getting into kilts! The girls won't know what hit them!

Andrew.