The least expensive all in one 88 key model on the market at the moment (with a stable OS) is the MO8. It's not an arranger though.

There's the Fusion 8HD (that sells for less), but if you buy this model you better get yourself a can of "Raid"--your music will be crawling with "OS bugs".

Squeak
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.