Suppose you are having good GPUs, which give you a hash rate of 600 KH/s. According to the latest calculation, you can earn 42.21 LTC every month, and 513.88 LTC per year.
less than $100/year?
doesn't look like a good deal
513.88 LTC per year means more than $900 at current exchange rates. From where did you got the $100 figure? Try Bitcoin mining and you'll earn even less.