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.
Eh, it could use the green color better, but it'll do. I like just having an aggressive deck like this in these colors, and the emphasis on really strong bodies with downsides is a fun experiment for newer players to learn how to play.
For budget- Maindeck cost is currently at ~$10.50 (according to the middle blue numbers on this very site under estimated value), sideboard at about ~$2.50, coming together just about $2 under my $15 budget.
So mostly this section is going to be notes on why I think these are good cards to learn from:
Starting at the bottom of the curve, Diregraf Ghoul is a classic black aggressive creature, Kessig Prolwer is a green Savannah Lion with a late-game mana sink for good measure, and Old-Growth Dryads are a pretty powerful body with a pretty powerful cost. Probably not actually good for the deck, but I'll be damned if it's not a cool way for players to learn how to understand tempo. It's a good Lesson, even if it's not that good a card. Can be replaced with any aggressive black 1-drop if players realize they don't want it. There's a 2/1 for 1 from Original Zendikar Block that deals damage to you unless your opponent is at 10 or less health that was in earlier iterations of the deck.
At 2, Wanted Scoundrels is a lot like Old-Growth Dryads- Probably not worth the cost, but at least they only benefit if they can kill this one, rather than getting extra mana to kill it with. Can be replaced with Erg Raiders, a 2/3 for 2 that hurts you if you didn't attack with it, if you're not a fan.
And Strangleroot geist- a fast, strong and aggressive creature that's been a green agro classic since it was printed. Good card, fun to play and relatively fair.
At 3, Pitiless Horde is an aggressively-stated creature that hurts you as long as it's on the battlefield, which is exactly what this deck wants, while Dreg Mangler is just good- a 3/3 haste for 3 is a strong aggressive card, and while I don't like having miscellaneous mechanics incidentally in these decks, players can easily ignore Scavenge and realize that the card is just good without it.
And Bone Picker, a card that I would've sworn would be more expensive than it is. Lots of things should be dying in this deck, so you should always manage to get this bad boy out for just 1 mana. A 3/2 flier for 1 doesn't need to come down on turn 1 to be an absolute beating.
As for spells- I love trying to get players to realize when to use Altar's Reap properly (ie, when their creature is about to die either way), Supernatural Stamina is a good card to let you get off a combat trade you wouldn't have been able to manage otherwise, and save your creature in the process. Could be Giant Growth if that's more your style, that'd be fair.
And Tragic slip as your only mainboard removal. It's cheap, and while it takes a morbid trigger to be good, when it works, it's a fantastic black removal spell.
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.
Child of the Night is a good card for putting yourself at a life advantage against other aggressive decks, while Mardu Skullhunter is a good way to attack slower decks right in the value.
Prey Upon is only alright in a deck full of low-health creatures like this, but sometimes it's the removal you need, and low mana cost is a huge virtue.
And the rest is just answers- Naturalize is great hate against many things, and Back to Nature is devastating against decks that need their enchantments.