Two places you ought to have the catalogs from anyway:
Certainly Parts Express. Parts-Express.com sells Speakers, Replacement Speakers, Speaker Building Parts plus HDMI Cables, Home Audio and Video, Pro Audio and Commercial Sound. We offer services for Speaker Reconing, Speaker Refoaming, Speaker Repair. Great selection of Elect PE has a large selection of speakers. Granted many of them are for hifi, but they carry a bunch of MI speakers too. Check out the Dayton house brand. PE also has tons of other speaker related stuff, like cabinet corners and handles, crossovers and crossover parts, jack plates, grilles, etc Get the paper catalog and leaf through it.
And wholesale only is Martin Sound martinsoundpro.com You will have no trouble getting an account. Call them and get a catalog. They carry a lot of Eminence, like the alpha through kappa series plus the guitar stuff. and some other brands you might not think of like Selenium. And those little piezo tweeters we find in "Acoustic" amps, LeSon or something like that? They have those. And a lot of diaphragms.
And don't overlook the tube sellers. Places like CEDist, New Sensor, Magic PArts sell speakers, and you may find what you want at a reasonable price at one of those. Or not...
When I want a real honest to god speaker, I usually look at Martin first. Like when I want something a little heavier for those Mackie SWA1501s.