If you are like most HS athletes, you have more time than money.
If you can't find someone (within driving distance) to donate some old standards to you ... build some.
Got to your local Home Depot/Lowes find the isle with the PVC pipes and get creative. For a base ... a bag of quick-crete poured in a 5 gallon plastic bucket with a 1" pvc pipe sticking out of it. Need more weight? Use more concrete or even sand.
Is it as convenient as a nice set of rolling, Gill standards? No. Is it better than nothing? Absolutely.
I hope you can find someone to donate some to you but don't let that get in your way. This is your own backyard so you don't have to worry with "regulation" just make it work. Keep in mind, generations of vaulters have had to use standards that were not much different then what I just described making and it didn't manage to kill off the sport
Hope it works out for you.