I wanted to expand on the tip from Sunny about using Christmas tree stands to create low-cost jumps. Here is a great site that shows pics of jumps (using PVC pipe) that were made this way:

Equestrian Training

From Christine at Equestrian Training:
Tips on drilling holes, use a jump cup then the holes stay even. Not everyone has a drill press, an absolute necessity to keep the holes straight on wood. A ruler and a jump cup (preferably plastic, will get your holes even and straight on the pvc pipe or pvc fence post. A word of caution. Some vinyl fences are not standard sized, and some jump cups will not fit.

Christine and BootZ