Digital BW, The Print

Does anyone know a source for pre-cut mats for 13x19 (Super B) images?

(Incidentally, Epson's specs for the 1160 say the minimum margin is .12" on 
all sides, but my OS X Epson driver demands a .56" margin along the bottom 
edge. Is anybody able to print with a .12" margin?)

I was talking with a professional framing/matting shop here in Seattle 
yesterday, and they said that 13x19 is considered a nonstandard size, so my 
only options (at least at their shop) would be custom mats or DIY. Pre-cut mats 
should be cheaper and easier.

Is this maybe a standard size outside the USA, and therefore available 
elsewhere?

Thanks,
Peter