One book I've used in my college darkroom course is "Photography," by Barbara Upton, et al., currently in its ninth edition. This latest incarnation retails for about $120 at Borders, though by looking around, you'll be able to get the sixth, seventh, or eighth editions for less.
While the price may make you gasp, consider how thorough it is; I still have my copy, albeit the fourth edition, but I continue to refer to it simply because it's so immensely useful. Because of this, you're not "spending money," but "making an investment," something which will pay dividends into the future.
