one man industry

1. one man industry

This should probably be written as "one-man industry" to indicate an industry that can be run by a single person. By hyphenating "one-man" you are indicating that it is a compound adjective and that "one" is related to "man" and not "industry." I say probably because, if the hyphen was omitted intentionally, then the phrase refers to a single industry that manufactures men. Quite often, the phrase refers to an individual who is exceptionally productive at a particular enterprise or task.

2. dream merchant

This is a figurative description of someone who makes a person's dreams come true by selling him or her something. I'm trying to find the origin of this phrase, but in the meantime I will note that it has often been associated with the film industry. A filmmaker is sometimes thought of as a dream merchant because movies can transport your mind to what feels like an alternate reality--much like dreams.