[TheDopp]

Valve makes more money by selling keys and this will go down if they start selling unusuals. Their business will take a hit.

That's why it won't be unusuals. It'll be something like paint, or an unusual crate that costs 25 bucks- randomly chooses one of say five hats, and from 5 effects. Rules would follow crate logic (2 common effects, 2 uncommon, 1 rare with a 1% chance of happening)
Example crate:
Hats-
40% chance of a coupe
30 % chance of a hallmark
20% chance of a fez
9% chance of veil
1% chance of tossle
Effects (same percentages and order, too lazy to type)
Green fetti
Flies
Smoking
New exclusive effect
Scorching

By having store exclusive effects of varying rarity Valve will be fine. Also retiring effects and bringing them back in crates/paints will also drive money