deatonent,
Sadly you're not going to get the 2000 and DGX in one keyboard. Now a 88 key PSR-2000 with the same keybed as the DGX-500 would be quite impressive... Currently the best route you can take would be an 88 key controller.... The cheapest one I've seen was nearly $500.00 and I think that was by "studiologic"...

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.