An ant tick dealer
A person who buys and sells bugs is commonly referred to as an insect dealer or insect breeder, depending on their specific activities. If they focus on selling insects for pet trade or educational purposes, they might also be called a bug vendor. Some may even use the term entomologist if they have a scientific background in the study of insects.
The proper identification is an entomologist, which is a person that studies insects. However, if you want to be very technical, a person that collects actual bugs, which are a type (or class) of insect, that person is called a hemipterologist.
A bad person. Unless you buy it and DON"T liKe it that's when you return it or sell it.
A person who buys a lot of things is often described as a shopaholic.
An author is a person who writes and sells books.
The person who sells drink is known as sellsmen
A realtor or estate agent buys and sells real estate on behalf of the principle, for a commission. They can also act as a managing company on behalf of the landlord.
baker
A bookie. Droll. You could call that person a bookseller or shopkeeper.
You call a person who sells flowers a (Florist)
A person who sells ship supplies is called a chandler
A person who sells jewels is called a jeweler.