Regular Budget: Bass guitar: 120-3000$
Bass amplifier: 50-2750$
Optional Budget: Bass pick: 8-12$
Bass strap: 15-60$
Bass case: 80-260$
Distortion pedal and processor: 25-600$
You may think that bass players are less skilled than guitar players and in some genres of music that is the case, but it doesn't always have to be. It takes quite a skill to play the bass guitar fast, using different techniques and exploring the whole bass guitar fret board.
While the most simple way of playing the bass guitar is just following the guitar by playing single notes in the background, depending on the chord that the guitar is playing, the bass guitar can do much more!
For example slap bass playing is one of the popular techniques that advanced players like Flea use, but sometimes just playing some smooth jazz can sound just as good.
Just because it has only four strings, though it can have more, it doesn't make it less worthy. Just like for the guitar, there are tabs for the bass guitar and they are read the same way. You can find most of the tabs songs here: http://www.ultimate-guitar.com/
To play the bass guitar you will need an amplifier. You can also use the regular guitar amp, but you will get a much better sound with a real bass amp. You can play either with your fingers or with a pick, the difference will be heard in the sound. Playing with fingers is more mellow and playing with a pick has a more sharper sound. There are also millions of different effects that you can use to make your sound more unique, that is, if you have a processor or a distortion pedal.
I guarantee you that you will enjoy this instrument, because it can be as smooth as a cigarette smoke in jazz and as sharp as a razor in metal music.