I have an 06 Trek Pilot that I have kept pretty clean. Lubed the chain when needed. I measured the stretch based on the Sheldon Brown article and decided it was time to change it. It was stretched 1/8 over the 12 inch measurement. I put 996 miles on the bike in the first season and have 2278 miles so far this season.
Bottom line: It took about 10 minutes to change. New SRAM chain cost $20.00. Check you chain often and don't be afraid to change it yourself.