Alana, the pictures of white Salpiglossis in your link do not look like the ones I have posted at ATP's PDB. Their picture was probably taken at the same location, or a similar one, it's the roadside on the way to Santiago's ski centres. A lot of people interested in flora visit those sites because of their easy access. If I wanted to visit the Andes from where I live, I would have to rent a helicopter, because I would not want to kill any mule with my excess weight LOL.
There is a lot of interesting native flora where I live now, but because of a serious draught (over 7 years now), rabbits and other rodents (I hate to say rats and mice) eat the whole plants before any seeds get to ripen.
I know I traded white Salpiglossis many years ago (whe the pictures were taken) at DG - I also sold lots of seeds on that site to finance a 'pay forward' project that probably included them. I no longer visit DG, but who knows, maybe you can ask if somebody has propagated them and has seeds to trade? At that time I also sold or traded a lot of our native seeds to Annie's Annuals, but do not remember if this white Salpiglossis was among them.
ursula