I say if the current kilt fits well and you like the design and style, I see no harm in copying the design.

As for fabric, yea I agree it would be a good idea to start with something cheap but wearable. Today I got enough fabric for one kilt for about $4.50 from Walmart. They had $2 a yard fabric and I seen a nice 100% cotton in a color I could live with and got it.

I myself am making my own kilt but I have no current kilt to go by so the results may be interesting. If I screw up too bad, I'll be out less than $20 total and maybe some time.

On a side note, let us see pictures throughout the process and when completed if possible.