Biggs lagoon in firestone isn't too far away from Ft Fun. Excellent frag selection and friendly folks. A bit on the pricey side, but I think that's just because they have higher end stuff. They've cut me deals before if I'm buying a lot. Besides, if you're in it to save money you picked the wrong hobby.
I've gotten some spectacular deals from Aqua Imports (hammer @$10/head), I think because they're mostly a freshwater store and didn't bother figuring out what some of their stuff was going for elsewhere. But the selection is somewhat lacking for corals.
I assume Denizens of the Deep in Fort Collins is long closed, no? I got my first corals from them 20 years ago. I'm pretty sure I bought a decent size bubble for 30 bucks. Now I can find only tiny frags for just under a hundred. Someone's got to do something about inflation in the aquarium hobby!