SRC CDs are now avilable from SRC Records
The Black Sheep CD is available at CD Universe as an import from the UK. CLICK HERE
You can sometimes find SRC recordings for sale on Ebay. The searches have been done for you:
Note that Ebay listings can vary from one day to the next. If you don't find what you're looking for, check back periodically. There are also some Ebay stores that sometimes carry them, so look at those in the search results as well.
You might also try some online used CD stores.
Happy hunting, and good luck!