Are you looking for oleander plants, oleander clippings or oleander soup?
The best place to obtain oleander plants would be to find an organic nursery . I am not sure of oleander clippings, but at one time there was a member of my Yahoo "oleandersoup" forum who knew a gardener who would package and ship oleander clippings for a reasonable price - but not via Paypal as far as I know. The best source by far of oleander online is the website for Sutherlandia OPC, which sells both an extract and capsule product made of 80% oleander and 20% Sutherlandia Frutescens (the South Africa "Cancer Bush"). The extract sells for $99 per 500ml bottle including shipping and the capsules sell for $70 per one month supply, including shipping.
Finding oleander soup in bulk form, or any oleander product with the USA might prove to be difficult. Though not impossible. Technically, since an oleander extract (Anvirzel) was submitted as an IND (investigational new drug) for FDA trials, it is not supposed to be legally sold for medicinal purposes inside the US.