I have just purchased a couple of the "Ventmesh" shirts. They are a little finer than the micromesh, and so don't look quite as casual - but they are stil very cool. I have found them to be great in Australia's hot summers (the last few games I have done, it has been 30 degrees Centigrade - around 95F outside, and probably 45/120 inside the stadium). Unfortunately very few Australian stadiums have airconditioning, so the extra "breathability" is a godsend.
I'm not sure how prices would work out, but the Aussie dollar is pretty week at the moment (around 50c US) so it may be worth checking out
www.coast2coastsports.com.au They are the
sole referee's distributor in Australia - maybe a bit of a market for any of you entrepreneurial types?