I get asked a least a few times per year whether I have a complete set of Nancy Drew books, Trixie Belden books, or some other series that I can sell to whomever asks. The prospective buyer asks how much the set would cost and what the postage would be. Depending upon the request, I may not have a complete set of extra books together. Sometimes I do, but I always reply that I don't.
Most of the books that I sell were purchased in partial or complete sets, which gives me a wholesale price. These days, complete sets sell for less than the total for which the books will sell individually. I am not interested in taking a complete set and reselling it for what I paid for it. I am also not comfortable with marking the set up to a much higher price and selling it to the person who asked. I also want the books for individual inventory, so the last thing I want is to get rid of a bunch of them all at once.
Sometimes I do sell sets of books, but this is always done to get rid of certain books fast without taking as much of a loss as I would if I were to sell an incomplete set. I decided recently to clear out all of my Nancy Drew Twin Thriller books that I had for sale. It was a partial set, and I determined that I would have to sell the books at less than what I paid for them. Instead, I put together a complete set of Nancy Drew #1-56 so that the Twin Thriller books would be part of a complete set.
I sold the set for $199.99 with free shipping, and the lot only took a few days to sell. After subtracting shipping and fees, I got around $150 for the books. I managed to avoid taking a loss, which was my goal. If I had decided to be patient with selling the Twin Thriller editions individually and had also chosen to sell the rest of the books individually, I would likely have gotten over $200 for the books. One does take less when selling books as a complete set.
Around six years ago, I had a strange request from a prospective buyer. This person asked me if I would put together a complete set of Motor Boys books in dust jacket for him. He wanted to pay me in advance and was willing to pay whatever I thought the books would end up costing. He didn't want to do the work himself; he wanted somebody else to find him the books. He didn't mind if it took a year or more for me to acquire the books. Remember, he wanted to pay in advance for this set of books.
I had a problem with this request for a number of reasons. I didn't want to invest my time and energy into searching for books for somebody else. I wanted that time to search for my own books. I was not at all comfortable with taking a large sum of money one or more years ahead of time for a set of books that I would likely have much trouble building. I also had no idea how much the books would end up costing and how much to charge. Last, I knew that if I spent a significant amount of time building this set that I would likely get attached to books and not want to sell them. Needless to say, I declined this person's request.