On Oct. 15, 1966, Grace Slick leaves the San Francisco band, Great!! Society!!, to join Jefferson Airplane. She replaces Signe Anderson, who left to have a baby. The one and only single by Great!! Society!!, “Someone to Love,” released on Northbeach Records can now sell for $450.00. The value jumps to $1,200.00 for a promo copy as seen here. Check out “Mighty John’s Promo Guide” in the yellow strip above for more examples of valuable promo records.