I'm ready to buy a new sound module and I'd like to buy one on a limited budget of around $600(Australian).
I'm mainly after grand pianos and electric piano sounds.
I have a 2005 Roland RD700SX stage piano set up at home.There are 3 banks of sounds catering for pianos:
1 for pianos,1 for electric pianos and the last bank covers a variety of every instrument.

I had an old kawai 76 note digital piano which had a nice fender rhodes electric piano sound.I miss that sound.

I dont want to add a 2nd keyboard just a sound module.Would you please suggest a good module?
Forgot to mention,I'm in South Australia.I dont mind where I buy within Australia as long as I can get it a lower price.