I can't say enough good things about the folks at Claymore / kiltrentalusa.  In brief, I needed a formal kilt on short notice for my nephew's wedding.  The guys walked me through the process and delivered as promised.  They didn't have the tartan I wanted available for rental, but we found a very similar substitute.  I had already decided to order my own kilt in my family tartan and it was delivered today precisely when and as  it was promised.