Jerry, the crumbling brick wouldn't work too well. Neither would the sale, seeing as the bunny and fanboy are suppposed to be limited. Wel, the fanboy isn't, but you get the idea. You should just be able to buy it with energy or Gems. they require you to do something and that's the way they want you to get the smileys. JackExtreme, grammar*. ;)
Demonicator, XD. Just spend your energy on one item only, and if that doesn't do it, try be online more. Your challenge is to be so active, that it doesn't EVER refill full! That way you can catch up.
SquidMan, nice idea. But maybe not 20, maybe 10. so every ten weeks or so, they release a theme wtih lots of smileys. For example, if the theme is jungle you will have these smileys:
Monkey;
Jungleman;
etc. Maybe also some vines, tree trunks, leaves, and so on?