How much electric power can we generate at home by use of treadmill like devices and dynamo?
A human in good shape can easily put out 150W for a sustained period, say a couple of hours.  A highly trained athlete like a professional cyclist can put out peaks of >400W or even close to 1 hp for a short time.

So if you cycled to generate power at 150W sustained for say 2 hours, that's .3 kwh.  You could store that in a battery and run an inverter to power your devices.  

With losses you might deliver 230 W-H and run a modern flat panel TV for 1-2 hours.  At the national average price of electricity of around $0.12 per kilowatt hour you would save $0.03 cents for the effort.

At your upper end of 1000 kcal you would generate 1162 WH and get back maybe 900 for a saving of maybe $0.10 on your bill.  If you do it every day you could save $3.00 a month or lots more if you live in a high energy cost state like CA.  You could watch maybe 3 hours of TV and run an LED bulb at the same time with that much energy.

The technology to do this exists and is relatively easy to implement, but humans are just not good generators of significant quantities of energy for the modern household.