I'm a guitarist of three years, and I really want to start playing bass guitar on the side. I've always had an interest in bass, but I've just never gotten around to getting one. I'm getting a job soon and I'd like some recommendations on some good beginner bass guitars for around $200. I'll need a bass amplifier as well, and I'd like something around the same price range. Maybe a little less... Around $150, maybe?

Can you help me out?
maybe a used fender MIM or a used ibanez in that range. don't really know much about amps but i got a 100w crate (bx100 i think) used for $100
If you're planning on just messing around on the bass at home and not gigging w it I would do $100 on a 15w Rumble amp by Fender and pay $250 for a Squier bass. Very good beginner basses!
For $200 or less, an Ibanez GSR200 or Yamaha RBX170 will probably be the best you can get new. If you're willing to go used, keep an eye on shops and on craigslist and see if you can't find something like a used Peavey Millennium or Milestone, or even a used Squier Vintage Modified or Classic Vibe Precision or Jazz. Any of those would be a perfect starter bass.

As for an amp, the Acoustic B20 and Peavey MAX 158 are good little starter amps that should fit into your budget. If you want to go used, keep an eye out for old Peavey combos or Kustoms.
Composite Aficionado

Spector and Markbass
Ibanez carries a beginner bass package for ~$190 (GSR190) with a 15W amp. It's not much of an amp but it can get you started for learning.