Um, well, without spending a large amount I can't think of anything.
If you're wanting to do budget, Elves combo might work. Though, it's much less a consistent turn 1 win and more of a turn 2-3 win (oftentimes without giving your opponent more than 1 or 2 turns thanks to Emrakul and the fact that the deck can kill on the play).
In order to hit turn 1 and 2 kills more consistently, you'd have to throw away the protection that makes the deck work through disruption, so expect it to be very one-dimensional.
there's two routes you can go. Utterly unfair with flash-hulk (which is actually a turn 0 kill at times) with lots of obscure cards or consistently evil with a Modern powerhouse, the Sam black mono-blue infect deck from Modern. It can get a turn 2 kill as well as some later turn ones but also packs tons and tons for countermagic in order to make life hard for your opponent.
The basic premise is this: Get a Flash, Hulk or Summoner's Pact and an accelerator card into your hand on your first or second turn. Flash the Hulk into play, do not pay the difference between Flash and Hulk, sending the Hulk to the graveyard. Fetch all copies of Shifting Wall and Phyrexian Marauder (their mana costs are zero, after all), fetch the 4 Disciples of the Vault and - BAM - upon resolution of the Hulk's ability, all 8 of the artifact creatures go to the graveyard for 32 life loss total on your opponent by turn 1 or 2. If you want to go overkill and kill a whole table, toss in Phyrexian Walker, Ornithopter, Memnite and Shield Sphere plus an Atog to completely kill a group of 4-5 people early, just to show you can.
The best part is: The above cards are about $.50-$1 each. The Hulks run about $2, and the Flashes run about the same. The problem is the Summoner's Pact, which run about $8 a pop. Admittingly, the deck would probably cost a grand total of $60, but a good portion of it would be spent in the Summoner's Pacts. There are replacements, I just can't think of any that enable the kill turn 1 and give you 8 virtual Hulks. Merchant Scroll is your Flash-fetcher, which doesn't help turn 1 kills, but it sets you up for turn 2 and 3 ones nearly guaranteed (as you're essentially running 8 of each combo card, and it's a 2 card combo that only requires 2 mana to "go off.").
Honestly I think your going a bit too spike. If its a school tourney just build a deck. If you were to build a turn one win deck, that completely ruins the challenge of magic. The fun of magic is there are two players both trying to win. Both players have a stratagey, system, and play style of how to acomplish that win. If you do a turn 1 win deck, thats unfun and the tourney organizer will probaly just ban you from playing that deck again. Again I assume this is just a casual tourney. Coming from a Timmy/ Johnny
Disciple of the Vault is banned... in Block Constructed, where you can only build your deck out of Mirrodin, Fifth Dawn and Darksteel cards. It's legal in Legacy, Vintage and Modern, the eternal formats (because it's obviously banned in Standard and Extended too as it rotated out of those formats a long, long time ago).
It's Flash that's restricted in Vintage and banned in Legacy. Though, he mentioned no banlist aside from some select, random cards, so it's not a problem (as you don't have to adhere to banned/restricted lists in casual play).
Sorry guys, but i've changed my mind about a turn one kill. As it turns out that Chancellor turn 1 kill deck some people were going to use is very inconsistent. So i'm using something else. My bad if I crushed everyone, and thanks for helping.
@Atanhe.....Yeah Demise OTK is terrible. Exodia FTK is better. Now back on topic.....