Rocky, I know it's easy to make suggestion when I am not the one having to carry the idea through, but here goes anyway:

1.For tartans you have in stock, a simple swatch or sample of chosen tartan. It may make choosing easier and less 'shot in the dark".

2. I know you include simple kilt pins with a kilt (nice touch too).
Have you considered stocking a wider range of pins to send out (at additional cost of course) with kilts?