Do your self a favor and look in the used market. I just picked up a 2000 Squire Jazz Bass with hard flight case (not the $50 cheapo ) and a small crate amp for $75.
I figure I've got around $50 or less into the bass if you consider the small amp and case. I just picked it up today so I haven't really given it a good setup or workout yet, but you can't beat that deal for in entry level Jazz Bass.
No need to buy new at $250 - $300 if you are just starting out.