Agree with pinkears, most greyhound rescues will take in whippets although they are more rare. You can also contact Scruples, a whippet specific rescue.
There are quite afew older whippets being sold privately on classifieds at the moment.
You just need to make sure you ask all the right questions about if the dog gets along with others dogs of all sizes, are they good with children and have they been worked(this may stop you letting it off a lead)

__________________