You can order decent quality kilts on ebay.co.uk.
Here are a few kilts that are available in the U.K with fairly cheap shipping to Europe. They are all Men's kilts and all fairly decent quality. All are around 50 euros (60-70 euros including shipping)
Scottish national tartan (I quite like this one)

Heritage of Scotland tartan

Douglas tartan

Mackenzie Tartan

Blackwatch tartan


This one is a set... kilt, belt and sporran for around 100 euros including shipping.


Good luck getting a kilt to suit you.

As far as the LARP is concerned, you might be best bringing it forward just a century. That way you can still have a lot of the medieval weaponry and ideas, but you're starting to get kilts and a clan system going.