If you like cyberpunk you will never go wrong with Snow Crash, though I had to read it twice before I understood the whole thing, great read though and I liked it so much I grabbed the Audible version for travel and background chatter. Not sure it's a $5 book though. Callahan Chronicles by Spider Robinson is also a fun read and not sure if it's so much scifi vs. social commentary wrapped in a SciFi blanket.
Out of the ordinary is Jennifer Government, Pattern Recognition. I really enjoyed Spin as well as Daemon. In fact, if you can ignore some of the stuff Orson Scott Card spews on occasion the Ender's series has some good reads. Ender's Game is the first and a good read. The newest Ender in Exile is good too but sort of does not stand on it's own despite what OSC says about it.
Speaking of whack job authors, L. Ron Hubbard's Battlefield Earth (the novel not the movie) was a book I really enjoyed even though I thought I would hate it since it was "that Scientology guy" who wrote it. He was actually a good SF author, again politics and whacked outtedness aside.
Otherwise, it really depends on what you normally read and if you want to venture outside that genre or stay within it.