i have a hai straightener, which i've actually read better reviews about from professionals than the chi...
basically the difference between a high-end iron and something you'd buy at walmart is the quality. they generally get hotter (mine goes up to like 410 degrees i think)..plus they are usually coated in ceramic which is gentler on your hair, and helps prevent snagging. i don't know if the ceramic irons you'd buy at walmart are of the same quality because i've never used one..
they are definately worth the extra money. I bought mine off ebay for about $50 less than it retails for.
we've discussed flat irons in these threads also:
http://www.greekchat.com/gcforums/sh...threadid=40593
http://www.greekchat.com/gcforums/sh...threadid=38161