This $15 deck combines a healthy amount of life gain with unblockable creatures, things to power up the unblockables, and a few midrange-ish creatures like Primal Huntbeast and Centaur Healer, which can be given Rancor or Tricks of the Trade to deal extra damage. I expect this deck to be quite competitive for its price. Beating most aggro decks (including RDW) should be cake, and it should be able to beat many other deck styles as well. Each part of the deck is explained below.
This deck's 1-drop is Cathedral Sanctifier. It can be put down on turn one, putting you up to 23, and can then act as a small blocker. Or if you keep it around long enough, you can gain some more life by returning it to your hand with Keymaster Rogue.
Our turn 2 creature is Invisible Stalker, likely one of the best unblockable creatures ever. In future turns, you can power him up with Rancor or perhaps Tricks of the Trade (if you have nothing else to put it on). And with Butcher's Cleaver, he will not only deal a lot a damage, but gain you a lot of life - and there's almost nothing your opponent can do to stop this.
On turn 3, a Centaur Healer can be put down. What's nice about this creature is that not only does it gain you some life, but it's also a 3/3 creature, ready to be given a Rancor or Tricks of the Trade for massive damage.
On turn 4, you can put down a Keymaster Rogue. Not only is it a 3/2 unblockable, but its ERB effect will allow you to bring back a Cathedral Sanctifier or Centaur Healer to gain some more life. And since it's a human, it also goes well with Butcher's Cleaver. Our other 4-drop is Primal Huntbeast. Since it's a 3/3 with hexproof, it's almost completely safe to put a Tricks of the Trade on it. Of course, giving it a Rancor or even a Butcher's Cleaver would make it pretty powerful as well.
As mentioned several times above, Rancor is there to power up your unblockables, and even if the thing you put it on isn't unblockable, you should be able to get some trample damage in. Tricks of the Trade makes your Centaur Healers, Primal Huntbeasts, and maybe Cathedral Sanctifiers unblockable, and if for some reason you only have unblockable creatures, it can at least power them up a little. Heroes' Reunion gains you a bunch of life for just 2 mana, but since it doesn't do anything else, it should usually be the first thing to sideboard out. Butcher's Cleaver gives a nice boost to unblockables, and in the cases of Invisible Stalker and Keymaster Rogue, it will also gain you a lot of life.
For our land base, we have 3 of each relevent guildgate. I didn't put 4 because we don't want to draw too many of these, since they come in tapped, limiting what we can do. If you have any duel lands handy, add them. If you have a playset, you can add all 4, no problem. There's also 5 Plains, Forests, and Islands.
In the sideboard is Elixir of Immortality for mill decks (and also you gain some more life), and Dissipate in case countering a certain card is important. Faith's Shield is there to protect Invisible Stalker from the few things that can remove him - Bonfire of the Damned, Electrickery, Chandra's Fury, Supreme Verdict, Terminus, etc. Unsummon to push back threats, especially threats that give themselves lots of +1/+1 counters, like Lotleth Troll or Primordial Hydra. I'm even considering mainboarding Unsummon since you can also use it to gain more life with Cathedral Sanctifier.