I have to disagree with most of the advise on this list. The tournament is going to be all decks that are <$6 a card from Scrye, which is notoriously overpriced. Additionally, Stompy functions on the assumption that there will be dual lands (Elite, Warbeast) and lots of Islands (as opposed to Mountians) and Necro (which is more than $6 in Scrye). Forbiddian doesn't work without Thawing Glaciers and Rishadan Port.
Here are the good T1 decks:
Donate
Zoo (Serendib/Savanah Lion/Jackal Pups)
Necro
Ophidian
Oath of Druids
all of those are way too expensive to play in you league. That leaves the second teir decks:
Sligh
Hatred
Stompy
Necro-less Black control
you can't play real control, because you need Moxen for that, and Disk is at least $6 in Scrye. Additionally, most control decks feature at least one key rare card that costs over $6. Finally, Hatred's/Black Weenie's inclusion is dependent on Hatred or Bad Moon being <$6. so here's the metagame for the under $6 league:
Sligh beats hatred, Black Weenie
Hatred beats stompy, White Weenie, Black Control
Stompy beats Sligh, White Weenie
White Weenie beats Sligh, Black Weenie, Black Control
Black Control beats Sligh, Stompy, Black Weenie
Black control
4 Vendetta
4 Vicious Hunger
4 Diabolical Edict
3 Contagion
3 Spinning Darkness
4 Hymn to Tourach
4 Hypnotic Specter
4 Wall of Souls
4 Black Knight
2 Drain Life
1 Demonic Tutor
4 Mishra's Factory
19 Swamp
SB (unless there actually are Blue decks)
4 Massacre
4 Perish
4 Death Stroke
1 Drain Life
2 Subversion
White Weenie
4 Mother of Runes
4 Soul Warden
4 White Knight
4 Soltari Priest
4 Warrior en-Kor
3 Paladin en-Vec/Thermal-Nightwing Glider
3 Empyrial Armor
3 Spirit Link
2 Cho-Manno's Blessing
1 Enlightened Tutor
4 Swords to Plowshares
2 Winds of Rath
22 Plains
SB
3 Disenchant
2 Enlightened Tutor
1 Spirit Link
1 Cho-Manno's Blessing
4 Honorable Passage
1 Light of Day
1 Conversion
1 Absolute Grace
1 Absolute Law
This is like a "Flores White" deck for the environment
Erik