Not sure how much longer it'll be on sale, but Documents To Go is only $5.55 as of this posting. Keep in mind that this app sells all day long at a regular price of $30, so that's a decent price.
Oh, to find it in the marketplace, search for "cinco" - It was a Cinco de Mayo special. Trust me, if the app's still on sale, it show up.
*note* - I'm not in any way affiliated with the application or the developers or anything. I just know that it's an app that a lot of us use, so I thought I'd share the info with you all in case you've been on the fence but thought that $30 was a bit high. (that's why I didn't have it, just too costly)