Option #1 Pre-purchase and have the collection shipped home.
Pro- $100 discount
Pro- guaranteed all the dolls in the collection
Pro- no waiting in shipping lines
Con- could be a month after the convention before you see your dolls (so as not to be disappointed, be prepared for a month)
Option #2 Pre-purchase and take the collection home with you or ship it yourself from convention
Pro- $100 discount
Pro- guaranteed all the dolls in the collection
Con- sales tax
Con- managing the transport of your dolls yourself
Option # 3 Wait to purchase at convention
Pro- only buy what you like
Pro- Take the collection home with you or ship it from the convention yourself
Pro- don't end up with dolls you don't want
Con- No discount
Con- Sales Tax
Con- No guarantee you will get all of the dolls ( usually only a couple )