I've been playing for a few years now, never took lessons. Just had fun with it jamming with songs and friends. I really don't have time for lessons but I wouldn't mind reading a book and learning by myself. I need something that isn't too complex.

Bass Guitar For Dummies

What do you want to learn? It would give us ideas on what to recommend.

If you want to improve your playing, then listen to more music and I always recommend Ed Friedland's books. Start with the 3 volume method book published by Hal Leonard. Then get some of the more specific books like the Blued Bass book (or you could start with that one).

Lessons might actually save you time as the teacher can pretty much spoon feed you what you need after determining where you are in your playing and what you want to do with it.

The Bass Bible by Paul Westwood is what I'd consider a good intermediate/ post-beginner bass book.

Its primary value is its decent outline of various popular styles, including some introductory study of playing in the style of specific greats -jaco, jamerson, etc...

I still use some of the generic rhythms for reading exercises.