A $3,000 snapon scan tool will tell you far, far more than any handheld OBD2 unit can.
Maybe your talking about something else, but you can get them for way less than $300.
I have one that feeds back basic "live" info, I think I paid $90 for it.
It has it uses, but you are not going to get much serious diagnostic info from it.
I tried searching Whitneys site out of curiosity ,,, I remember getting their catalogs all the time years ago - But my searches kept coming back as "your session has expired", so I couldn't see what they have to offer.