For example: 1 year is worth $9/year and 2 year is worth $17/year Why? Shouldn't it be otherwise like everything?
Actually in first year you can get discount by coupons but in 2 year registration there is rarely coupon available
Well now I see an increase at GoDaddys price, it's now $11.99 for 1 year domain and for 2 years it's $12.49, 10 years $12.89 not a big difference right now :S But I wondered why does the price increase instead of decreassing as a discount for larger purchases?
Why some do the more years you register will be cheaper is because it encourage you to register more year in one time . If like your situation , they sell 1st year is cheaper is because they mostly do promotion on 1st year and the promotion code usually discount with the fix amount for the 1st year only.
JerrickYeoh is correct. It is not cheaper the second or third year, the price is the same. Domain companies lower the price for those registering more than 1 year in order to encourage longer registration periods.