Yeah, I had a frag setup once, but it was too painful to keep two setups... It would be much simpler with a basement sump to plumb off of, but with the main tank self contained in the living room, it's pretty tough.
Normally I do try to help out the local reefers or trade for credit (although local stores can't keep SPS), but the area's reefing crowd is dwindling, and I unfortunately keep missing swaps. I'll check with ABC next time I head up. I usually just "suffer" with stuff in the main tank until I find takers.