Because the flag of our people is a single color, you will probably find it somewhat pricey to go and purchase a custom flag just to get the right shade of purple. In fact, it may even be better to DIY your own flag with any flag and a coat of paint since that makes it more personal and stops the consumerization and appropriation of that flag and the ideas it represents.
While officially the flag is Lavender, a shade of purple that is too bright makes it appear white. It is recommended to actually use a darker purple than how you want it to appear in reality. Darker purples may not be exactly Lavender, but it’s functionally the same flag. Nobody else is using a purple flag as far as I know so the shade does not really matter.
If you live in America, the national flags sold in stores are definitely not suitable for hanging up in the state you buy them in. It is a ritual to take a flag of your country and paint it over with Lavender. Making a flag like this is symbolic of being free from the nation you were born in and being able to choose the spirit world instead.