I FINALLY, FINALLY finished this slouchy beret. I ended up frogging this (at various stages of near-completion) a total of seven times after running out of yarn. It was as much my stubbornness as my lack of money that caused me to absolutely refuse to buy a second skein. ;-)
I first tried to use the entrelac beret pattern here http://knitternutter.blogspot.com/2007/01/entrelac-cap.html
and frogged that six times while trying to figure out the sizing and how to get something slouchy out of one skein before realizing it was impossible. I guess all the picking up stitches and p2togs/ssks eat up the yardage. Here's me looking mopey when the entrelac finally defeated me.
Then I used the purl bee's pattern here which specifically states it only uses one skein of Koigu http://www.purlbee.com/beret-purl/
. Apparently this is only true for the traditional sized version (read: NOT slouchy). So I frogged it one more time, cast on 12 fewer stitches and adjusted the decreases accordingly. Success! At least after all that frustration, I can say I'm really happy with the finished product. (More details on my misadventure on the requisite blog.)