Starkeeper,
Actually when I had the PSR-540, it was only one of several keyboards I owned.. I got married, and things got pretty crowded with all my stuff and my wifes.. It actually was best for me to sell some of my keyboards because we really didn't have the space for them, and I was working so much that many of them rarely got played. I ended up selling it, and later on down the road wanted another small affordable keyboard like it.. The PSR-550 seemed to be the best choice for me because I really liked the 540.. Only now it was better because the 550 had improved sound quality with new voices, better styles, music data base, looked way better, and had a multi color back lit screen.. This to me was a great choice. If I remember correctly, music123.com sold it to me for less than the killer price they're selling it for now! I think they're selling it now for $469.00 I got mine for less than that! I gave them a few price quotes I got and they blew all of them out of the water...

Squeak