Lets start with how many basic types are there to begin with (not counting the sports bags):

Formal bags to take to work

   Envelope bag     Doctor bag    Kelly bag         Tote(shorthandle)    Satchel

Casual bags to match your casual, informal wear.

             Tote             Hobo               Messenger           Swingpack         Beach bag

Evening bags for social events and evening get togethers

                   Clutch                   Envelope Chanel         Minaudiere

How many do we need ?

Atleast

One casual in leather, one beach or summer bag, one sports bag

One formal

One evening

and you will find yourself sorted, as far as the handbags are concerned.

Happy reading..