If you're buyuing only the under hood stuff, but are going to replace all the stuff you list, it sounds like you're buying the compressor mounting brackets, the idler pulley and a few odds and ends..... $150 seems high for that. You haven't addressed the issue of the evaporator under the dash or the vacuum motors that operate the many flaps which may need replacement as well.
Try Classic Auto Air in Tampa. FL. They've got a great illustrated catalog that list's absolutely averything.