For the old farm look. See if anyone is re-doing their deck or fence. The weather wood for those make great building materials. Also look for farm auctions. That is a great way to get cheap farm products for your scene.
If you have a Big Lots near you, a couple weeks ago mine had some Wagon Wheels that were like $18 or something close to that. They were Big, and totally usable in a Farm haunt type of situation.... I want to say they are like 30 inches tall....
Get a bunch of hay bales (usually about $4.00 each). Stuff bones and body parts into them, so it looks like people got stuck in the hay baler. Hands, feet and an arm or two sticking out would add to it. Splash some red paint around on them and you are good to go.
You can often get "mulch grade" hay bales for half the price of hay that is of feed quality to keep costs down.
oh and don't forget the cages of scary animals in the dark you could pull that off without any real animals pretty easy use some recorders and put something in of similar size that makes people think there's a dangerous animal in there.
you could make a chicken coop with some fake chiken parts use some mangled looking fleshy things break open a feather pillow and toss the feathers around and coat them with blood and then buy those cheap ravens and cover their beaks etc in blood make it look they are eating the dead chickens or whatever animal you might have in mind. You could probably get the gross parts of the chicken feet head that's been chopped off etc from a farm that sells chickens not sure where u live at but if in the country you could even do that in advance freeze them and thaw them closer to Halloween and get some of the props in advance that way.