This searches the sites listed in on this page, with the exception of Cambridge University Press, Rutgers University Press, Boydell & Brewer, and Brook's Publishing which must be searched separately.
You'll need to skip ads at the beginning (powered by free Google Custom search).
Another option, is to look for texts published by university presses or scholarly associations--these non-profits offer high quality, often at moderate prices.
Or, you can seek out small specialty publishers with expertise in specific fields. Texts from these "niche" publishers can be both high quality and reasonably priced (see examples among the Texty award winners at right).
Some texts from scholarly and specialty publishers have won awards!