Like Macktee I took advantage of the sign-up offer several years ago. When I renewed I took advantage of the three-year deal which gave me each year at the sign-up price if I paid for all three at once. See if they have a similar deal now.
This form of marketing is widespread in the retail business. Magazine subscriptions are a great example. The idea is to get you to try it and like it so your willing to pay the full price on renewal. If you don't like the value at full price you can decide to not pay. This is not much different than any other spending decision you make in life. I see little reason to get angry at the retailer for this. Their other option is to offer it at full price all the time.