1. A computer-based recommendation system for generating recommendations of unique items, the recommendation system comprising: one or more computer readable storage devices configured to store: a plurality of computer executable instructions; an items information database containing data relating to a plurality of unique items; one or more hardware computer processors in communication with the one or more computer readable storage devices and configured to execute the plurality of computer executable instructions in order to cause the computer system to: receive an input from a user that comprises user-expressed preferences associated with the plurality of unique items; calculate a customization score for each unique item in the plurality of unique items, the customization score representing an estimated preference impact based on at least one customization attribute that may affect the user's preference for the unique item; calculate a condition score for each unique item in the plurality of unique items, the condition score representing an estimated preference impact based on at least one condition attribute that may affect the user's preference for the unique item; generate a dissimilarity penalty for each unique item in the plurality of unique items by combining the customization score and the condition score, the dissimilarity penalty at least partially generated based on a magnitude of dissimilarity between the unique item and the user-expressed preferences; and generate a recommendation of unique items by ranking at least a portion of the plurality of the unique items based at least partially on the calculated dissimilarity penalties.
1. A computer-based recommendation system for generating recommendations of unique items, the recommendation system comprising: one or more computer readable storage devices configured to store: a plurality of computer executable instructions; an items information database containing data relating to a plurality of unique items; one or more hardware computer processors in communication with the one or more computer readable storage devices and configured to execute the plurality of computer executable instructions in order to cause the computer system to: receive an input from a user that comprises user-expressed preferences associated with the plurality of unique items; calculate a customization score for each unique item in the plurality of unique items, the customization score representing an estimated preference impact based on at least one customization attribute that may affect the user's preference for the unique item; calculate a condition score for each unique item in the plurality of unique items, the condition score representing an estimated preference impact based on at least one condition attribute that may affect the user's preference for the unique item; generate a dissimilarity penalty for each unique item in the plurality of unique items by combining the customization score and the condition score, the dissimilarity penalty at least partially generated based on a magnitude of dissimilarity between the unique item and the user-expressed preferences; and generate a recommendation of unique items by ranking at least a portion of the plurality of the unique items based at least partially on the calculated dissimilarity penalties. 14. The computer-based recommendation system of claim 1 , wherein the condition score further represents an estimated preference impact based on at least one status attribute that may affect the user's preference for the unique item.