Dealerships always rape you on parts and service, but I think that is the least of your problems. What the hell are you doing to your car that "your clutch and other related parts" are shot at 26K?!
If you are a good driver and havent beat on the car (do you race?) I would question the mechanic- but that seems unbelievable to me- having to replace a clutch on a Honda with low mileage. If you do decide to fix it, just take it to an independent mechanic to compare prices, although I don't know what, if anything, that would do to your warrantee. Do you have a detailed list of the parts they wanted to replace?