I think the cheapest you could reasonably expect to get a useable synth with a decent keyboard is $300, independent of age and coolness. That's where you'll find a Microkorg or a Mininova or something.
Of course you can get romplers and keyboards with preprogrammed sounds much cheaper. And you can probably do something quite nice with a Behringer JT-4000M (once it hits the shops) and a cheap MIDI keyboard.
Of course you can get romplers and keyboards with preprogrammed sounds much cheaper. And you can probably do something quite nice with a Behringer JT-4000M (once it hits the shops) and a cheap MIDI keyboard.