I'll let you know when I find one. My list of owned cues includes, Richard Black, Tim Scruggs, Tascarella shafts, Robert Dzuricky, Andy Gilbert, Troy Downey, Skip Weston, Scott Gracio, Mike Capone, Bill Stroud - to name a few - many of the best of the best- I consider every one of those cues as straight cues. Some of them were bought from members on this site- I never argued straightness with any of them.
Again I will say that I will take a consistently straight stroke over a shaft that rolls PERFECTLY flat from tip to joint any day of the week. IMO way too much is made over cue shaft straightness- 99% of them are not perfectly straight. Even if they come out of a shop rolling perfectly flat- 99% will not stay that way forever.
I say just buy the best equipment one can afford and worry more about how you play than what you have in your hands. I've seen way more strokes that are far more crooked than the cue being stroked.