I should also have mentioned that the Best of Sets will each be available until March of 2014, so you don't have to buy them one at a time. They are just introduced one per month.
The Paper Pumpkin kits will be different each month (forever) except for the Welcome Kit (first kit you get - has the acrylic block) and the Try it Kit (just a one time purchase to try it out - also has a block). So once a month has passed, you can't go back and get an older kit as far as we know. Just the Welcome and Try it kits will remain the same for a while they said - perhaps a year.