If it were in my budget, I would 100% have also thrown the Sanguine Bond + Exquisite Blood combo in this deck. That shit's just funny.
So this is a project I wanted to engage in- To make a set of 10+ super-budget 60-card decks that are simple, relatively easy to play, relatively easy to understand, and bring across the fundamentals of how Magic Works. We've since gone way past 10, with tons more in the works, and I've really enjoyed the challenge of trying to make these decks easy to play and understand, fun, and all under a $15 budget, sideboard included.
The main goal here is that you could easily build these deck for a low cost and use them as an easy introduction to how magic works, to teach a group of new players both how to play, and give them a sense of Why, a sense of what fun things they're getting into. These decks aren't gonna be particularly good, or even legal in any particular format if it stops me from including a card I think is good for the deck, but they should be fun and interesting without being too hard to get into. They should be an easily-accessible example of how fun Magic: The Gathering can be.
This is one of the more advanced decks- Not really the first decks you want people learning with, but a sweet, budget deck you can use once new players are already on their feet to really knock their socks off and get them to think about something you can do in Magic that they might not have otherwise realized. Alt-win-conditions sort of automatically get you in that category, you know?
This one didn't come together as well as I was hoping, but it's still silly and fun and I like it, but I'd rather be playing either of the other two silly, janky combo decks I've just made, and both of them were kind of a mess too, just a more fun mess. But Triskaidekaphobia is a sweet card, and it's silly and fun to play around with, and it feels like a sweet card to play against an unprepared opponent.
As for budget: Maindeck cost is currently at a little less than ~$10.40 (according to the middle blue numbers on this very site under estimated value), sideboard at about ~$4, since a bunch of the more expensive cards ended up there.
So mostly this section is going to be notes on why I think these are good cards to learn from:
Triskadekaphobia is the obvious mvp here, and your intended win condition. You need to be able to carefully manipulate your opponent's life total, and your own, considering you need to not die to your own triskadekaphobia... or just die. Both are important concerns.
To the end of you not dying, you have End Hostilities, Immolating Glare, Last Gasp, and Pacifism to defend yourself with.
To the end of manipulating life totals, Soulmender can be your emergency "Anything but 13" button, and can also keep your life total up a little, Orzhov Guildmage is mana-hungry, but can do some fine point-manipulation of life totals, and Vizkopa guildmage, equally mana-hungry, can be used for different options and similar purposes. Most importantly- Damnable Pact lets you pay X mana to deal X damage to an opponent. Sure, they draw cards, which is far from ideal, but if you can set them to 13 that way quickly enough, go for it, they might not have ways to pay or gain life. You should also, you know, cast it on yourself to draw cards much more often, but it seemed like a sweet addition to the deck as a potential way to set up Triskadekaphobia kills.
All of these options are mana-hungry, so to mildly abate this problem, we run a playset of Hedron Crawler. Not fantastic, but it'll do.
Finally, Diabolic Tutor, to tutor up whatever effects you could possibly desire.
Manabase is meant to be a touch lacking, but also super-budget. I'll be doing the same for all of them.
As for the sideboard, this IS supposed to be a sideboard they learn how to use, to make their deck perform better in the right matchups, or just in general to customize their decks within constraints.
Death Grasp is for if you think the somewhat mana-intensive "Your Life total now equals 13" button is the way to go, and want to stop giving your opponents cards for the trouble, extra End Hostilities for board-wiping, Read the Bones for card draw, Devour Flesh seemed like a hilarious card in this deck, to give some more opponent lifegain, as well as a useful removal spell, Harm's Way is normally a sweet card in these decks, and here is a hilarious blowout since you can use it to instant-speed put someone's life at 13. And Mortify remains a good card always.