What I mean to say is that you can get unreserved ticket from Coimbatore station only for a specific date (3 days advance booking is allowed for unreserved tickets). Why to get down at Kurduwadi for buying ticket as the train halts only for 1 minute only. If you are not able to get at Coimbatore station, then try at Solapur station (Solapur to Kopargaon or Manmad) The train halts for 10 minutes at Solapur.
Note one thing that at Daund, you will have to shift to General Unreserved coach for your journey to Kopargaon.