Theory / History Texts

Hi everyone, I'm new here.. I'm a teenaged piano student going to be playing my gr8 (conservatory canada) exam on Tuesday (shudder). I have a question concerning theory and history texts the conservatory requires for next year's written examinations.

For history, The Enjoyment of Music by Joseph Machlis, Kristine Forney (plus the accompanying scores and recordings)

For theory, Eighteenth Century Counterpoint by H. Gilbert Trythall & Harmonic Practice in Tonal Music by Robert Gauldin

Does anyone have any experience with these books?, for some there are workbooks available, would you recommend them?, and how would I go about ordering them and how much are they going to cost me... I know these things can get expensive but I'd like to have a general idea. I've looked at my two local music stores don't carry them and weren't able to help me order them (clueless teenagers behind the counter).

Thanks,

Chelsey