One good hting about jumps is that you don't necessarily need standards...
Any of these can also be used as "standards" with poles on top of or resting on for cavaletti/cross rail style jumps:
Empty 55 gallon drums (two feet 6 inches lying down, 3 feet standing up)..standing up can also be used with two poles to create about a 16 inch crossrail or lying over top the barrel, a full 3 foot jump.
Overturned 5-gallon buckets
Stools or chairs
Cement blocks (as "standards" vice fillers..don't want the horse hitting these)
Traffic cones (fillers..hard to use as standards).
Plastic window boxes can be filled with plastic flowers and used as fillers
This time of year, corn stalks make great fillers to practice brush jumps.
Use PVC pipe for poles..they come in various sizes, can be painted or kept white, are light, durable and gentle on legs.