Under $150, you're pretty much begging. I'd cruise pawn shops in your area, especially if your area has a live music scene to speak of. You're probably going to end up with a Squier Affinity, First Act or similar bare-bones entry-level instrument. Basses with more recognizable labels selling at this pricepoint probably have something wrong with them, which you may or may not be able to fix.
If you can even double your budget, you'll start getting into respectable product lines of some of the more well-known import brands. Personally, at the sub-$300 level I'd be looking at Yamaha. Yamaha have a reputation as learner's instruments; affordable, with the priority being feel and playability, then sound, and looks last. As such, they don't tend to look like much on the wall, but they'll feel much better in your hands. Avoid the 17x line of instruments, they're Yamaha's attempt to compete at the very lowest pricepoints and it shows. Pretty much anything in the BB, RBX and TRBX series with a model number 200 and above will be a quality if basic instrument that can be set up for excellent playability and will give you a good sound. $300 will give you access to most new 200-series models, and older used 300 and 400 series.