Lots of left handers play right handed (including yours truly). Before you plunk down the money, go into a store and try them out, and see which was feels more comfortable. Always made sense to me to play right handed - my strong hand is my left hand, which does all the fretting. But see which feels good to YOU.
As to instruments, if there are used music stores or pawn shops out where you are, hit them up. Not likely to find a left handed bass, but assuming you are playing right handed, I've seen Squiers going used, in decent shape for $99 all day long. You also may find a used amp.