Are the book clubs worth it? Used stores?

I keep seeing the tear-off post cards in my books for their book clubs(yes Im reading the cheesy $3-10 romance novels). I read so much that it would cost a fortune to buy books at the rate I read them, think one to three small books a night or one of the paperbacks with two or three stories each.

Im trying to figure out a cheaper way to get new books but are the book club deals from the publishers worth it? What about used book stores?Are the book clubs worth it? Used stores?
I use a website called paperbackswap.com. They let you trade your old books for books that you haven't read yet. You post books you would like to get rid of and every time you mail one to someone you get a point that you can use to get any other book on the site. You can make a wishlist so if a book you want isn't posted you will get it when someone posts it. You only pay to mail books to other people and that usually costs under $3 and you can print the postage from the website so you don't need to go to the post office.Are the book clubs worth it? Used stores?
I also use paperbackswap.com and it's great. I wouldn't sign up for those tear off offers, they can be misleading.