Sorry for the lateness of the post, but rest assured the thoughts behind it were there.
The C-Store is in my Opinion, an example of the best way to implement additional funding for a MMO. The Champions store allow you to purchase in game items (non-combat related). You actually purchase points (like with XBox live) and then apply those points to whatever you want. Of course non of the prices related directly to the amounts you can purchase, so you will probably always be left with some points tempting you to purchase more, even if it's just so you can hit zero.
The really nice thing here is that they also chose to allow account items to be purchased here. For example, want more toon, buy them in sets of 4. I don't know if there is an account limit for total characters, but I know you can get at least 16 (if you got the lifetime subscription, which now I wish I had) which is double the 8 you get by default. I honestly can't think of what I would do with more than 4 at this point, but I think a big part of the game is playing the game with different powers.
The other big account option is that you an purchase more alternate costumes slots. In game you change your costume on the fly, and max level characters will have 3 outfits to choose from with a 4th for the supergroup (Guild) should you join one. You can edit the costumes at any time for a fee based off the changes, but having other looks that you can swap to is also a nice touch. You can tell there is alot of character design that went into making sure this is a good looking game.