Bass is the unofficial "backbone" of most bands, providing the perfect synchronization between the drums and guitar. But how do you get one? Easy. To get the basic starter bass, I say save at least 250 dollars (for bass and amp).
Most people think Fender or MusicMan basses due to their popularity, but most people don't realize that you can't get one of those for under 500 dollars most the time. Start cheap and work you're way up. Good brands to start out are Squier (Fender owned cheap replicas), Epiphone (cheap Gibson replicas and very cool bodies) and Ibanez (an all-around cheap company). An added plus is that you can get many Value Packages which will include an amp for under 300 dollars.
I myself started on a basic 1 pick-up SquierBronco Bass, an easy short scale bass which is nearly identical to a FenderP-Bass. The one thing you need to lookout for is the pick-ups. I made the mistake of buying a one pick-up bass which I have paid for dearly (literally). I had to pay an extra 90 dollars later to get another pick-up placed in. Pick-ups shape the sound of your bass. You need as many as humanly possible.
Next, Amps. Which amp do you want? There are many brands that sell cheap amps, but are they worth it? Fender brand amps are known to blow after about 2 years. While Crate has an amazing reputation for sound and durability. I myself own a BX15 Crate bass amp which sounds like a 25-30 watt even though it is only 15. One amp that suprised me was the Washburn brand. Known for guitars and basses, I expected the amp that came with my guitar to be crappy, boy was I suprised. That little 12 watt cranked out like no other. After I took off the protective grid on the front, it doubled the sound.
Next and lastly, though not majorly important, I suggest a good effects pedal. If you didnt get enough pick-ups, some pedals can completely change the sound of your axe. Digitech sells a pedal with 81 effects in it, its insane. Inside it, it has 31 drum beats for you to play along with. Great practice material. For reference, the name of that pedal is the RP50. An incredible buy for the 80 dollars I spent on it. I mainly mentioned the things i own but thats because I want to spread the word on these wonderful starter items. Good luck bassits and spread the word the bass is making a comeback.