The most economical way to build a collection is without doubt buying specimens. Remarkably,the commercial value of a shell generally falls just below the cost of finding such a specimen yourself. Furher, when working with the right people, specimens will come to you all cleaned and labeled. Also, you have access to the most desirable items in the conchological world. Those are often very expensive to discover in nature.
Many of these glorious beauties are seen only rarely in exchange lists, and are difficult to obtain without paying hard cash. The problem for collectors purchasing shells lies in obtaining the less commercial families which, because of their low price, are seldom offered for sale. Purchasing complete collections of common shells is a solution.