Are there any alternatives to real cash to obtain objects listed in the in-game shop?

In Portal 2 there is an in-game shop similar to the Mann Co. of TF2. Are there any alternatives to real cash to obtain objects listed in the shop? Is it possible for these items to drop while gaming like in TF2, for example?

Solution 1:

Besides the hat for beating single player you can get the WCC Flags from the High-Five achievement.

You can also load things from TF2 in Portal 2.

Solution 2:

I haven't seen any drop yet. That said, you get a hat when you beat single player. Haven't beaten co-op yet but that may give a hat as well. Also one hat if you have it in TF2, you also get it in portal.