casiobot,
You can use any compatable style to create your song on the PSR and Tyros series of keyboards, and editing is a snap as well. Some folks need a computer to edit their songs, but I'm not among them. Additionally, most of the songs on the PSR-tutorial site were not created using PC software, and there have been some fantastic songs posted on that site.
The price of a used PSR-2000 in good to excellent condition is currently about $500. However, finding one can be a difficult task. There are a lot of performers still using the 2000 and wouldn't part with them at any price.
Good Luck,
Gary
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Travlin' Easy
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PSR-S950, TC Helicon Harmony-M, Digitech VR, Samson Q7, Sennheiser E855, Custom Console, and lots of other silly stuff!
K+E=W (Knowledge Plus Experience = Wisdom.)