I know you said "locally" but if you can't find what you need you should try CoralVue's site. I've personally purchased metric plumbing parts there for my CADLights system.
For my 45g I started dosing Polyplab's One. I don't follow the instructions though since that tank only has smaller SPS corals. I dose 1 cap every other day and my levels are stable at 8.5 for Alk and 440 for Calcium. I don't test for Mag.