I'd go with something used if you want cheap, you'll get something much better for the price. I'd go with the something in the yamaha line for all in one like the RS-7000, R1MX or SU-700
rs7000 is a good bet...
but if you don't need sampling,check out the Emu XL7.The command stations offer 16 tracks of sequencing and has the ability to add roms for more sounds.