Let me ask you what you want the new kilt for, with USAKilts the under $100 option would be a casual kilt, whereas if you were to go to Still-Water for that money it would be a more traditional cut. I do not have an SK, or a kilt from Frugal Corner, so I do not know anything about their products first hand.
I would think the first step would be to figure out whether it would be a casual i.e. sitting on your hips, or a traditional i.e. sitting above or at your navel.