Where to find it: If you're happy with the standard design, you can get a Hydrapple ex for less than $5 on TCG Player
Sure, a lot of cards recovered well from the last two Modern Masters sets, but they had less supply, and MM15 boxes appreciated much less than MM13 before them (partially due to lessened set value)
So you can simply turn all your forests sideways, add some green mana, and attack with a 6/6 commander or so
For smaller tournaments like League Challenges, it's usually enough to eat before leaving for the tournament and after getting back
Starting with the first player, each person can put any number of cards in their hand on the bottom of their deck
Exiling cards from players graveyards