As you are probably on a budget and as you stated are new to keyboard thing, I would suggest an older synth, workstation or even an arranger. Something cheap to really learn about keyboards and texture creation. You could get several keyboards and still keep it under a thousand dollars. Say a Yamaha DX-7, Ensoniq ASR-10, Roland D-50, Kurzweil K-1200 (or even a PC-88) maybe even a Generalmusic S2(3), Generalmusic Equinox. Now none of these that I mentioned are arrangers, but everyone of them are professional instruments that are still used on stage today, and will teach you a lot about midi, sampling, FM synth, Sound texture etc.. Things that will make you a better musician and give you the ability to create your own sound and style. IMO is almost more important than your playing still, as this will make you sound different, which differentiates you from others that use stock sounds.