Your thrifty friend Kello here, to tell you that from September 25-30 there is a "Back to School" sale on a bunch of great comics over at Things From Another World. Most of the sale items are considered "nick and dent", which means they have some wear or tear. Although it may sound like the site is going to sell you a bunch of junk, I have bought these items and found no noticeable differences in quality.
I just spent about $100 and got 13 trades (including newer Captain America, Thor, and Punisher collections!) and 28 single issues.
And yes, there are plenty of FF comics on sale, too. Happy hunting!