The Roland 303 is a cool little machine.  I've never owned one I am sorry to say but I've had many of 303 patches for samplers and they are some of the best bass sounds I've heard.  This machine ain't much to look at resembling one of those cheap casios you used to be able to buy, but it can stand up as the reigning champion of bass synthesizers.  In this soundfont you get 30 tones to use.  Click on the 303 to download the file.