take this from a lefty musician. Learn right handed while you can.
Best advice you'll hear, trust me on that, it'll take about a week or two of feeling its wrong then it'll be fine and you'll thank yourself further down the line.
Your bank manager probs wont tho
*Edit* if you're absolutely hell bent on getting a left handed bass, try the lefty market thread in my sig, "whynot" is seling a nice started bass for £80 and he's a great guy to deal with
Then again you could probably get a similar quality right handed bass for half the price
Mixed messages or what?