Okay so i am a bass player and want to expand what sounds i can make and pretty much when it comes down to it bass effects suck Because im looking for synth type stuff. So i figure what the hell ill get a synth. Most of this stuff is way to far over my head right now. What im wondering is if anyone can recomend a synth that meets these requirments.

-Can produce synthy leads as well a ambient noise and layers
-At least 49 keys
-has bigger keys than a micro korg
-relativly easy to use
-under 500 bucks
-ohh and i prefer something new and something i have the potential to try out before i buy it

Im willing to go anyway i need to whether its digital or analoge or computer bassed, multiple keyboards what ever it takes to get what i want. Ohh yeah and if it helps the band i play in is very much influenced by dredge, mars volta, led zep, circa survive, saosin, the sounds of animals fight, fall of troy, you know all those bands that are or have ambiant parts in their songs where synth could be thrown in as well a straight up leads.