29.5mm I.D. Seatpost needed--Ideas??

[Steve in SLO]

I am in need of a long seatmast topper with a 29.5mm inner diameter. I am thinking of using a cut down a 31.6 seatpost. Does anyone know where I might find a list of I.D. measurements for alloy seatposts? I Googled and couldn't find any lists...talk about esoteric info.
If all else fails, I am going to take my micrometer to all my LBS's and check every seatpost in stock.
Thanks for any info.