The API are excellent and are generally classed as "high-end" preamps. They retain thier value. Easily a better buy over any mid-level pre that I know of personally.
Keep in mind that the API's need a power supply. The price you have is for modules, and you'll need a rack supply which is about $600 or more. You would be cheaper going with the John Hardy stuff, which is also considered "high-end", but probably better off with the API just for resale purposes.
I think the Hardy rack is $500, and the preamps are $400 each, give or take. Good expansion possibilitie though, after initial expense, you can add preamps for $400. The Hardys are known to be very clean as in Great River category.