A cheaper set of strings for you and some history. I never noticed an endorsement by Macca though.
http://www.proaudiomusic.com/accessories/bass_guitar_strings.htm#La%20Bella%20super%20stepsOur History
The Family Behind the Strings
The Mari family began making violin strings in the town of Salle, Italy, in the 14th century. It was in 1640 that the Mari family came to prominence. For centuries their factory supplied the finest strings to violin makers including Amati and Stradivari. By the 20th century, the House of Mari was one of the largest manufacturers of musical instrument strings in Italy. It was during that time period the Mari family began to sell their best strings under the brand name "La Bella."
New York City became the new home to brothers Emilio and Olinto Mari in 1916 when they opened a factory near Union Square, producing both gut and steel strings. Eleven years later, Italy awarded E. & O. Mari with its Gold Medal Diploma, an award and an honor to the Mari brothers for excellence in manufacturing.
At the start of World War II, E. & O. Mari closed their Italian factory. Later, shortly after the war ended, the brothers moved their factory to Long Island City, New York. E. & O. Mari remained on Long Island for nearly 40 years after which the company moved to its present location in Newburgh, New York.
E. & O. Mari is still family owned and operated, continuing over three centuries of quality and innovation. The current Chairperson is the daughter of Olinto Mari, Elisabetta Mari Cocco, and the President is her son, Richard Cocco, Jr.
E. & O. Mari is a proud supporter of the arts and music education worldwide, sponsoring artist appearances, clinics, and an annual Bass Summit concert. A special highlight is awarding the La Bella Grand Prize to the winner of the Guitar Foundation of America's prestigious solo guitar competition.
Where it All Began
The origin of the use of catgut for the strings of violins and kindred instruments has, from time to time, been explained in various ways. The most interesting, and probably the most authoritative explanation seems to be the one known among violin makers in Italy for centuries, but little known outside the country.
The story is related by Joseph Primavera, who gathered his material in the little town of Salle, Pescara, Italy, a town that has had for almost six centuries the making of catgut strings as its chief industry, and from which some of the finest strings in the musical world have come.
It all goes back to around 1300 AD, it seems, when Salle was already famous for its saddles. Not the least important feature of these leather products was the fact that a thread made from the intestines of a mountain sheep was used in sewing them. This thread was found to be far stronger than that made from more domesticated and better cared for sheep of the valleys.
Tradition at Salle says that at the dawn of the fourteenth century one Erasmo was employed in the chief industry of the town, the making of saddles. As this man was drying some sheep intestines in order to make his thread, some were carried away by the wind, and became lodged in a thorn bush.
Erasmo noticed that sweet musical sounds were emitted as the material was vibrated by the wind blowing through the bush. Being an observant man, and an ingenious one, the thought came to him that the threads used in sewing saddles might also be used as strings in the primitive instruments that were ancestors of the violin. Thus the business of making violins strings from "catgut" (more will be said later regarding the origin of the word itself) began, and so important did the industry become to the small town that eventually Erasmo was sainted, and St. Erasmo is not only the patron saint of the town, but also the profession of string making.
When asked regarding their strings, the people of Salle, so the tradition states, said that they were made of the intestines of cats, "catgut". There was good reason for this. The cat was viewed with superstition in Italy, and the slaying of a cat was supposed to be followed by a period of bad luck. The fiddle string makers of Salle reasoned that few indeed would attempt to copy their trade, if it involved slaying cats.
Mr. Primavera, by searching church records, found that from the beginning of the industry in the time of St. Erasmo, until about 1700, four centuries, the families of Berti, Dorazio, Mari, and Ruffini were famous for making violin strings. These families furnished the strings for products of Stradivarius and other master makers of violins during this period.
About 1640, Mari Brothers became the leaders in the manufacture of "catgut" strings. This tradition is followed today by the same family, now located in Newburgh, New York, USA under the company name of E. & O. Mari. Many of their products are marketed under the world-famous name "La Bella" and are recognized as the finest strings available.