Digital BW, The Print

Ok, here is a newbie question. Are there any entry-level 
densitometers out there, new or used, that will be acceptable to be 
used with b&w output from piezo printers? In other words, I am not 
interested in color issues, transparency media, etc.

I would like to use the densitometer to compare papers, inks and to 
setup my own curves.

Are there any other reasons for me to have a densitomer?