I tried playing with the electric piano virtual instrument in Sonar today, but playing an actual piano / keyboard is far far easier for me.

Unfortunately though, my DGX 630 wont fit on my lap while I'm using the toilet :(

The Yamaha PSR series like paulo mentioned will give you more bang for the buck. I think they are around $200. Good luck! 

I've gone for the Akai Synthstation 49 mainly because I decided I would prefer a VA kind of sound plus rompler sounds. I can use FL Studio/Garage Band etc. for recording ideas...I got one for a knock down £80.
 
Only problem is that when the iPad is plugged into the keyboard it cuts off the iPad's speaker so I've had to also purchase a Bluetooth/aux in speaker so I don't have to use headphones.
 
On the Yamaha front I was amazed at how much you can get now for so little money with the PSR range, my first keyboard was a PSR (27 years ago I think!) before I went synthy with a DX-27.
 
 

Sounds like a good option, but you did change the rules on us quite a bit there ! ;)
 
 

paulo
Sounds like a good option, but you did change the rules on us quite a bit there ! ;)
 
 

As always I like to keep my options open and I did explore them all =)

I'm late to the party here.  Was going to say I have a nice Yam PSR sitting up in the loft looking for a new owner.  I replaced it mid last year with an Akai only because it had better control/pitch wheels and a smaller footprint.