I was able to grab all six of the "Preview Series" of Kreon Micro-changers at Toys R Us today. Since Kreons are the most interesting part (in my opinion) of the whole KRE-O line (which, for those who don't know, is Hasbro's answer to LEGO), it was an easy decision, and one made easier by finding out online that the "blind-packed" pouches really aren't all that blind-packed at all. However, this fact isn't readily obvious from the packaging, so consider this post a Public Service Announcement to help you avoid getting duplicate Kreons you may not want.
At the bottom of every pouch, look for a number. You can safely ignore the first five digits. The important part here is that last number ("8" in the example to the right). So long as you can avoid buying pouches with the same last number, you can safely avoid getting duplicates.
But that's not all! With the help of this handy chart (which came packaged inside the pouch), the information is widely accessible to know exactly which character you'll be getting inside that pouch! As with most pictures on this blog, you can click the thumbnail to see a larger version, which you may especially want to do in this case. The numbers associated with the characters on this list follow a somewhat different format than the ones on the pouch. I'm not sure why. But the last digits do line up precisely, so in the case of the pouch with the "8" on it seen above, this chart tells you that the Kreon you'll find inside is none other than Galvatron! So even if you don't want to buy all six Kreons at once (although, at a mere $3 each, you very well might), as long as you have this chart, you can easily ensure that you're buying the character you really want.
Happy Kreon hunting!