A couple of purple books are available at Amazon.com. Or like a shade of purple. Asimov.
The Currents of Space (Galactic Empire series Book 2) for $2.99.
I found a copy of The Complete Stories, Vol. 1 for $2.99. This appears to be a cheap bootleg. No publisher is listed on the product page. There are page numbers and copyright notices mixed into the text. Missingspaces abound. It was published in February of this year. I very nearly bought it. Be wary.