u seem to ride it daily for 25-30 km so if the avg consumption of cg 125 is 40-45 at its best then think if u can bear it .. go for it .. its a reliable machine .. the only concern to u should be the fuel price .. if thats a no issue in this case than its a good choise.. also from time to time u will need to have some outing with ur friends and believe me 70 cc bikes are a big pain for double sawari.. 100cc are ok.. but 125 is awesome..
incase if u cannot bear the mileage of cg 125 then buy a 100cc bike that will give u something close to 50 - 55 km/ltr and u wil have both power and economy ..
for 100cc u can get either honda , suzuki,yamaha. or chondas... in chonda there is unique ud 100 with disc brakes and alloy rims and also is the zxmco these costs approx 60k .. if u want resale consider junoon or honda cd 100..
hope this clears much of ur confusions.. if any left tell us that..