First off, sorry for the not-included price in the subject. The calendar that I have has a tiny bit of paper ripped off, and it happens to be the bottom half of the first number, so I can't tell if it's 25 or 35 bucks off the Town Plan. If someone will verify for me what the calendar says, I'll be happy to update the title. Anyways...
From the Lego Store Spetember 09 calendar:
Save $25 off Town Plan!
Item 10184. Cannot be combined with any other offers. Code 4588423