Borrow your buddies pickup truck in the fall or spring and drive down the streets of any nicer upper middle-class neighborhoods, but not too nice (they might call the cops on you). If they are typical Americans, they will be giving away one of the best mulch/fertilizers bagged up and sitting there on the curb ready for you to steal. Fill up your truck with the bags, but not too full - you don't want to get pulled over for driving an overloaded vehicle. If you are a smooth talker you might even get the home owners to pay you to take away their 'trash' so that it is not sitting there until garbage day.
Take them home and pour the leaves (not the bags) through a shredder if you have one, or just dump them out in a protected area so the wind doesn't blow away you loot. An 8'x8' area with a 4' high chain link fence makes a nice container (or any fence for that matter - T-Bars and pallets work quite nicely). Fill it up and go back for more bags. Keep piling on until you are worn out - you will be surprised how fast they compact down, especially if shredded. You should be able to get an 80% reduction by shredding, plus another 50% by compaction, so 8x8x4x5x2=2560 cubic feet of unshredded leaves, assuming eight cubic feet per bag = 320 bags, assuming 20 bags per pickup truck load = 16 truck loads... so you better get moving. Beer helps - but pick a designated driver.
If there is not much rain that season, you might need to wet the area down occasionally. Be sure to dig down in a few areas to collect a bucket of earth worms whenever you go fishing. If you started in the fall, they will definitely be ready by spring. Feel free to mix in your fireplace ashes (after completely cool), it will help neutralize the acidity of the leaves. Just pull open one side of the fence, and dig in to the richest leaf mold that you can possibly steal.
If you have a particularly mean streak, borrow a different buddies truck, load up your leaf mold and drive around those very same neighborhoods offering to sell it back to those very same people you stole the raw materials from originally :-)