I would buy the best quality kilt I could afford. In most cases the young folk have a disposable income that allows them to buy quality. When you are older there is always something that one has to cover mainly food and lodging caring for offspring and the elderly!
If you outgrow the kilt you can sell it or save it for your son or other family member. The beauty is a traditional wool full 8 yd kilt will last, look better than a cheap kilt! There is no comparison, most of the members here lust after a traditional well made kilt. Admit it!
You may be able to get a 2nd hand properly built traditional kilt. When I was a teenager, that was when I was able to afford the best in clothes and electronic gear.
Go for it, you will be glad you did!