sounds steep here too. i personally would only put in the dealer belt, and the dealer tensioner. the pulley should be replaced if indicated (i.e. the bearing is seized or rough).
is the Dayco kit the brand on the belt too? if so, i'd be leery. i can't find the discussion right now, but here or at one of the other forums, the discussion about what belt to use ended with a JLEMOND chime in which seconded the dealer belt and one other belt brand (only). maybe he or someone else will chime in here too before i can find that thread.

consider calling st charles
http://isuzu.stcharlesauto.com/Department-Parts.aspx
or pm'ing JLEMOND (who may sell the oem parts); check prices, get educated on quality, and then maybe return that dayco stuff.

while a regular isuzu line technician can do this job pretty quickly, i'm told, the first and only time i tackled it, it was worth it but time-consuming and i wouldn't want to do it again too soon because of an inferior part(s).


//bc