Clean up get() calls, remove commented out code

@Ignat99 PTAL.

As suggested by @dionyziz at https://github.com/OpenBazaar/OpenBazaar/pull/658#issuecomment-56653243 I created a PR out of my own code-review comments.
Your style is cleaner. :)

I don't know what should be done if the `item_price` is absent. I suggest we first refactor the code clean, so that