* You do have to pay for parking. It's either $5 or $7, I forget which.
* Bring something in which you can comfortably carry a lot of books - shopping carts are at a premium, and there's often a waiting list for them, plus they're hard to maneuver down the aisles. Rolling suitcases work well. The sale will allow you to bring in just about any kind of carrying apparatus you like. While they do offer free handled bags, the handles start cutting into your hands when the bags are full, and they do get heavy!
* The highest price I've ever seen on one of the books (that is, regular-issue books - there is a rare book section where I'd suspect prices are higher) there is $8. Paperbacks are mostly a buck.
* Sunday is half-price day. I tend to go both days, because, by Sunday, the books are pretty well picked over.
* You want to allow plenty of time - if you get there early (like, before noon), there is quite a line to get in, and they only allow about 100 people into the place every 20 minutes. Then the sale itself is so big that, if you are looking in a number of different genres, you can expect to be there for a couple of hours. Word is that people start lining up around 4:00 am.
Enjoy - just don't take that last copy of a book I've been searching for!