Get black dustbin bags and get some white paint and splatter over and this gives like a starry night illusions and is very effective, we did it as an art project at university.

for Grave stones, get some large boxes and cut bottom half into a rectangle and top half into an arch shape attach both if done seperateley, paint grey with black writing and red blood dripping and paint on.. if you have any black cat toys or birds attack to top of it.

For your house, if you have a dollar shop, buy things like cobwebs and dress the house up..

I could easily do a house up on budget for 10 dollars and it would look great.