I'd say drop [c]Descendants' Path[/c]. The chances of you flipping up a creature are about 1 in 3, and not enough of your creatures share a type for it to be useful, you're looking at getting an extra card 1 in every 9 or so turns--so only one or two extra cards per game. Other than that, everything looks pretty much like it'd work. As long as you can ramp up quick enough you'll be fine.
Also, I know you said you weren't looking to spend money on the deck, but the 2013 commander pre-constructed decks that're in stores now are only thirty bucks--which sounds like a lot for only one deck, but it's got a ton of rare cards in it, and a bunch of lands that are especially helpful for commander. Specifically, the "Nature of the Beast" deck is pretty similar to what you're trying to accomplish. If you got that and pulled out some of the weaker cards and mixed in what you have, you'd have a pretty awesome casual commander deck.
I highly recommend buying at least one commander deck just because there are so many "necessary" cards that they come with. But in the end it's all about the fun you can get out of it, so if you're pretty evenly matched against your friends with what you've got, then stick with that.
