Free: Contests & Raffles.
If your on a tight budget, save up some money and by a dozen or so big foots. Then go to www.divebombindustries.com and buy some of their silos. One dozen for ducks and geese is less than 70 bucks. I use their stuff especially when the ground is soft and I don't want to tear up a farmers field or get stuck, so I pack in. I'll pack out a few bags of my Dakota full bodies then Throw in the silos and walla. I've killed tons of geese and ducks over them. Investing at least some money in to your spread is worth it man. Having birds come close is only fun for so long, you want those birds to finish up for you. Plus, sky busting birds who are already Leary, does not do anyone any favors. I like to figure 6 full bodies for every 12 silos if you decide to go that route.
Keep your eyeballs on outfits like Rogers Sporting Goods, Macks Prairie Wings, etc. for good sales too.