most important card: this card only comes in one printing, so no matter where or how you get it, it will be the right one (unless it is marked "proxy," which is highly unlikely)
https://www.cardkingdom.com/mtg/modern-horizons/yawgmoth-thran-physician

all the links below go to specific printings of the card

cards under $2 each
https://www.cardkingdom.com/mtg/scars-of-mirrodin/leaden-myr
https://www.cardkingdom.com/mtg/rivals-of-ixalan/dusk-legion-zealot
https://www.cardkingdom.com/mtg/modern-masters-2015/reassembling-skeleton
https://www.cardkingdom.com/mtg/kaladesh/weaponcraft-enthusiast
https://www.cardkingdom.com/mtg/modern-horizons/carrion-feeder
https://www.cardkingdom.com/mtg/battle-for-zendikar/smothering-abomination
https://www.cardkingdom.com/mtg/promotional/desecrated-tomb-draft-weekend-foil
https://www.cardkingdom.com/mtg/khans-of-tarkir/bloodsoaked-champion
https://www.cardkingdom.com/mtg/commander-2018/phyrexian-delver
https://www.cardkingdom.com/mtg/masters-25/zulaport-cutthroat
https://www.cardkingdom.com/mtg/commander-2017/butcher-of-malakir
https://www.cardkingdom.com/mtg/duel-decks-zendikar-vs-eldrazi/pawn-of-ulamog
https://www.cardkingdom.com/mtg/ravnica-allegiance/gutterbones
https://www.cardkingdom.com/mtg/commander-anthology/ghost-quarter
https://www.cardkingdom.com/mtg/war-of-the-spark/bolass-citadel
https://www.cardkingdom.com/mtg/modern-masters-2015/everflowing-chalice

$2-$5
https://www.cardkingdom.com/catalog/search?search=header&filter%5Bname%5D=karn%27s+bast
https://www.cardkingdom.com/mtg/promotional/heros-downfall-clash-pack-foil
https://www.cardkingdom.com/mtg/modern-horizons/force-of-despair
https://www.cardkingdom.com/mtg/commander-2015/phyrexian-reclamation
https://www.cardkingdom.com/mtg/commander-2016/astral-cornucopia
https://www.cardkingdom.com/mtg/commander-2017/decree-of-pain

$5-$10
https://www.cardkingdom.com/mtg/shadows-over-innistrad/westvale-abbey
https://www.cardkingdom.com/mtg/commander-anthology-vol-ii/solemn-simulacrum-219-b
https://www.cardkingdom.com/mtg/commander-2014/ob-nixilis-of-the-black-oath
https://www.cardkingdom.com/mtg/ultimate-masters/all-is-dust
https://www.cardkingdom.com/mtg/commander-2017/black-market
https://www.cardkingdom.com/mtg/iconic-masters/kokusho-the-evening-star
https://www.cardkingdom.com/mtg/battlebond/diabolic-intent
https://www.cardkingdom.com/mtg/masters-25/coalition-relic

$10+
https://www.cardkingdom.com/mtg/scars-of-mirrodin/lux-cannon
https://www.cardkingdom.com/mtg/magic-origins/liliana-heretical-healer
https://www.cardkingdom.com/mtg/commander-anthology-vol-ii/grave-pact
https://www.cardkingdom.com/mtg/war-of-the-spark/liliana-dreadhorde-general