You say you ARE a rookie photographer--so, do you already HAVE a camera of some sort? Because, as KmH points out, it's really, really hard to be a photographer at all without one!
I'm going to assume you have NO camera at all, and have simply borrowed cameras before to know that it's something you want to do. If this is a wrong assumption, it could change my advice.
My advice--if $150 is really all you can afford, and you don't foresee that changing anytime soon--get a Canon Powershot, the best one you can get for what you can pay.
I used a Canon Powershot for years before I could finally afford to make the leap to a DSLR. If you're TRULY a "rookie" there is MUCH you can learn and do with even a basic point-and-shoot. Composition is SO critical to good photography, and you can work on that with ANY camera. Additionally, decent point-and-shoots like Canon Powershots allow you to shoot in manual mode, so you can begin to learn to do more than stick the camera in Auto mode and point, and shoot.
I managed to win several photo contests (judged contests, not popularity contests...) with my little Powershot, so I know from experience how much can be done with them.
DSLRs are great; I love having one, and I can do a lot more with it than I ever could with the Powershot. BUT--if all I had was $150, I could spend it on a Powershot and still be perfectly happy with the results I'd get. There will be plenty of time ahead of you to get the DSLR--but even if you get a cheap, used one, next you'll need/want another lens, then an off-camera flash, then a better lens, then...it NEVER stops. And it AIN'T cheap!
EDIT: I'm recommending Canon Powershots because of MY experience with them--I'm sure the cameras suggested by Robin, or tirediron, or others are just as capable, or more so. Point is, don't sweat it! There's plenty of decent options out there--get one, learn with it, then when you can afford it, upgrade.