The Roland Juno-D is also a good entry level synth and has a budget price tag.
While you can sample the sounds from other keyboards they will never quite respond to playing like the original keyboards. So if there are Privia sounds that you need to keep then you'd need to keep it to play those sounds. Plus it has the weighted key action that you won't find on a synth under $2,000
You probably should keep using the Privia and either add another keyboard or modules for extra sounds. A rack mount keyboard module is simply the same synth engine as a keyboard but without the actual keys so only requires a rack mount sized space but needs to be triggered by MIDI from a keyboard .... like your Privia. It saves space and also is usually lower priced. But maybe you want to have a second keyboard so you can play both at the same time if you have both stacked in front of you on a double stand.
[This message has been edited by Nigel (edited 07-15-2007).]