Back in the mid-1980's I ran into the same price differential from "on-line" retailer (actually it was a paper mail-order catalog back then. Anybody else remember those?) and a local bike shop. I wanted to buy a ring-type multi spoke wrench and had seen it in the catalog for about $3. I happened to be near a local high-line bike shop in town and asked about the same tool. They had exactly the same thing (same maker and model, not Campy) and wanted $12. I passed. A few days later I happened to be near another LBS and asked them about the wrench. They also had the exact same tool and wanted $4.50. I bought it without a second thought.

I have no objection to paying a bit more for immediate ownership and to support a local business but not a 400% cost penalty.