You might check this site out:
http://www.yamahamusicsoft.com/

With all due respect, I think that Scottyee is wrong. Your PSR2000 has the ability to read Scorch XF files, which are midi files that display scrolling sheet music on your keyboard display.

If you want to save money, the newer version of Band In A Box (http://www.pgmusic.com/) can create editable fakebook-style lead sheets from any midi file. Using http://www.musicrobot.com/ you can search for specific midi files on the web. There are also downloadable "fakebooks" especially for BIAB on several sites... do a search for "Band In A Box fakebook".

And finally, there's no need to cart heavy fakebooks around... I use a flatbed printer/copier to copy the individual sheets from the fakebooks and put them into non-glare sheet protectors in a 3-ring binder.