vivo barefoot aqua, dharma, or lesotho are the best and most expensive as you noted. if you have the $$ they are worth it. also the most 'work' looking shoe of the lot.
a finnish company, feelmax, makes a line of really minimal (read thin and flat) shoes. the osma is their 'running' version and costs appx 80 bucks. kind of looks like the onitsuka ultimate but even less shoe. really helps pf. if too thin simply add a thin flat insole (ie spenco).
converse all star new model, the allstar slim, is appx 50 bucks. also very good, and more flexible than the original. now that the sole of cons are made of a composite along with rubber, rather than the original which was a more flexible full rubber sole, the sole is not nearly as flexible as in past. the slim has exactly the same canvas upper, but is more flexible due to thinner composite/rubber sole.
there are others, but these come to mind.
vivo via their terraplana site, feelmax via amazon or extremeoutfitters.us, and cons via zappos.