I use a Casio EX-F1 that I bought >2 years ago; however, anyone interested in slo-mo video for baseball should probably consider a newer, lower-priced alternative from Casio:
The Casio EX-FH25 can be purchased within the range of about $340 - $400 (depending on where you shop) and its got great specs for recording high speed video.
[Disclaimer: High speed video requires lots of light–note that all of my clips are taken outdoors. Even a well-lit basketball gymnasium is typically not sufficient for high speed video. People who need to use these cameras indoors for analysis of their swing or pitching mechanics, etc, will have to consider rigging up high-wattage shop lights to make usable slo-mo videos.]