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.
I was trying to comb together more color and archtype combos I haven't done before, and realized that not only do I love Hundred-handed One, but I hadn't actually used it yet, because I hadn't done any White Midrange (And to be fair, White isn't amazing at midrange.), so here we are, in a Selesnya deck with so much Vigilance it can choke on it.
As for budget: Maindeck cost is currently at about ~$10.50 (according to the middle blue numbers on this very site under estimated value), sideboard at about ~$3, which all adds up nicely.
So mostly this section is going to be notes on why I think these are good cards to learn from:
From the bottom up- Aerial Responder is a sweet card that gains you lots of life, Boon Satyr is a really good card with two very useful modes that are both super-playable in midrange decks at about this mana curve, Citadel Castellan is sweet if it manages a successful attack, passable if it doesn't, and adds to your density of White permanents for Abzan Kin-Guard, who, alongside Aerial Responder, should ensure that you gain enough life to fight agro, while both are still totally playable against non-agro decks, which is nice.
Do not under-estimate the value of a 3/5 Vigilance for 4. If there were a vanilla one of those, it'd probably be in a bunch of these decks, but instead we have this bad boy- can pump up to a 6/8 if you sink in an extra 6 mana, and can block for days. Sweet card, wonderful to have in the deck both early and late.
Your big payoff is Serra Angel, a beloved classic that I haven't used in as many of these decks as I'd like. Solid card, great card to learn with, good top-end to kill 'em dead with.
For Card advantage, and a 3/3 just because, Mouth to Feed is a wonderful card, Your removal spells are Immolating Glare to play defensive, Pounce to be a bit more aggressive, and puncturing light for little things.
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.
Untamed Kavu is the other card I was considering besides Serra Angel for the top-end of this deck. Both are good, and I liked the idea both of players being able to choose which of the two cards they like better, as well as boarding in more top-end depending on the matchup.
Extras of your 5-drops for matchups where the lifegain creatures are less important, Soul's Magesty is a serious Value card for serious value matchups (and there aren't that many in Selesnya, so make it count), Naturalize and Plummet are narrow answers that are real good in the right matchups, and thus perfect sideboard cards, and Reprisal and Celestial Flare let you tailor your removal options toward the higher end of the spectrum.