Before we get into the "how to" please read this to get an understanding of how this system assigns a specific registration price to an individual.
Everyone in Higher Logic is assigned to registrant classes. They may be assigned to several classes, or none, depending on their membership status. (sometimes in the system they are also referred to as security groups). More about member types.
When you set up your event you will be given the option to assign prices according to these registrant classes.
Then you will be able to select which prices you want to set up. You can choose some or all.

When someone comes to register the system will look up their registrant classes, and start working down the list of prices, following the order you see above. If they are a Chapter Member Individual it will assign that price. If not, it will move on down the list until it finds the first registration class that the individual is in, and it will assign that price. The non-member price is set so that it will catch everyone who hasn't been assigned to a class.
(Be careful if you have set up a complimentary or admin price! You must set the non-member price too, or some people will get the complimentary option because they weren't in any other registration class)
The information that follows will show you how you can over-ride this waterfall process and set the system so an individual is assigned a specific registration class for your event, that you choose.