Cheapest way:
Find the ceiling joists (studs are in walls
).
Sink an large "eye-bolt" into it. An eye-bolt has a wood-screw on one end, the other is a closed loop. You'll need to find one with a large "eye" to accomodate a C-Clamp.
Use a C-clamp to connect the bracket of the light fixture to the eye-bolt.
I would VERY HIGHLY recommend using a saftey-cable from the fixture to a second eye-bolt.